Clean air research

Transcription

Clean air research

ISBN 978-952-62-0292-1
Clean air research at the University of Oulu 2013
SkyPro Oulu Clean Air Cluster
P.O. Box 4300, FI-90014 University of Oulu
E-mail: skypro@oulu.fi
www.oulu.fi/skypro
Clean air research
at the University of Oulu
Proceedings of the 2nd SkyPro Conference
November 12th 2013, University of Oulu, Finland
2
Place and year of printing: Juvenes Print, Oulu 2013
Cover design and layout: Heidi Pruikkonen
Photos: SkyPro Oulu and MHTPL, the Thule Institute photobank and iStockphoto
ISBN 978-952-62-0292-1
CLEAN AIR RESEARCH 3
CONTENT
POLLUTION PREVENTION AND CONTROL
Catalytic emission control studies in the Mass and Heat Transfer Process Laboratory at the
University of Oulu
Riitta L. Keiski, Mika Huuhtanen, Tanja Kolli, Kati Oravisjärvi, Marja Kärkkäinen, Mari Pietikäinen,
Anna Valtanen and Ari Väliheikki...........................................................................................................................
New knowledge for the industrial CVOC emission abatement
Satu Pitkäaho, Tuomas Nevanperä, Lenka Matějová, Toni Kinnunen, Satu Ojala
and Riitta L. Keiski.....................................................................................................................................................
The chemical composition and alveolar deposition of particles from an off-road diesel engine
Kati Oravisjärvi, Mari Pietikäinen Juhani Ruuskanen, Seppo Niemi, Mika Laurén, Arto Voutilainen,
Arja Rautio and Riitta L. Keiski......................................................................................................................................
Renewable hydrogen from ethanol: Reforming at low temperatures over Ni supported catalysts
Prem Kumar Seelam, Anne-Riikka Rautio, Mika Huuhtanen, Krisztián Kordás
and Riitta L. Keiski...............................................................................................................................................................................
Catalytic oxidation of dimethyl disulphide over monometallic Pt, Cu, and Au catalysts supported
on γ-Al2O3, CeO2, and CeO2-Al2O3
Tuomas Nevanperä, Satu Ojala, Satu Pitkäaho, Nicolas Bion, Florence Epron
and Riitta L. Keiski......................................................................................................................................................
Total oxidation of dimethyldisulfide over Cu-Pt-based catalysts
Bouchra Darif, Satu Ojala, Laurence Pirault-Roy, Mohammed Bensitel, Rachid Brahmi
and Riitta L. Keiski......................................................................................................................................................
Total oxidation of dichloromethane over platinum based catalysts
Zouhair El Assal, Satu Ojala, Mohammed Bensitel, Laurence Pirault-Roy, Satu Pitkäaho,
Rachid Brahmi and Riitta L. Keiski........................................................................................................................
Dichloromethane oxidation over noble metals supported TiO2-based catalysts
Lenka Matějová, Satu Pitkäaho, Jana Kukutschová and Riitta L. Keiski....................................................
Trends of polychlorinated dioxins, -furans, -biphenyls and polybrominated diethyl ethers in bank
voles in Northern Finland
Mari Murtomaa-Hautala, Matti Viluksela, Päivi Ruokojärvi, Arja Rautio..................................................
CO2 MINIMIZATION AND UTILIZATION
Decarbonization of Europe by 2050: Motivation for Smart Energy Network development
Eva Pongrácz, Arttu Juntunen, Jean-Nicolas Louis and Antonio Caló.........................................................
Via CO2 photoreduction over nanocrystalline TiO2 towards valuable products
Lenka Matějová, Kamila Kočí, Zdeněk Matěj, Satu Pitkäaho and Lucie Obalová.................................
CO2 emission mitigation in ironmaking with biomass: Replacement of coal with biomass in coke
production
Hannu Suopajärvi, Juho Haapakangas and Timo Fabritius........................................................................
Sustainability assessment of commercial and CO2-based synthesis routes of Dimethyl carbonate
Paula Saavalainen, Eva Pongrácz, Danielle Ballivet-Tkatchenko and Riitta L. Keiski.............................
Sustainability assessment of formic acid production: Comparison of conventional and CO2-based
processes
Linda Omodara, Paula Saavalainen, Eva Pongrácz, Esa Turpeinen and Riitta L. Keiski........................
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Utilisation of industrial by-products and waste in environmental protection “NO-WASTE”
Niina Koivikko, Satu Ojala, Satu Pitkäaho, Nicolas Bion, Catherine Batiot-Dupeyrat,
Ulrich Brökel, Michael Bottlinger, Rachid Brahmi, Mohammed Bensitel, Sergio Botelho,
Joachim Zang, Shudong Wang, Liwei Pan, Riitta L. Keiski..............................................................................
The influence of electric vehicles on CO2 emissions: Challenges on infrastructure in cold
climates
Antonio Caló, Jean-Nicolas Louis and Eva Pongrácz........................................................................................
Home automation to reduce CO2 emissions associated with energy consumption of buildings
Jean-Nicolas Louis, Antonio Caló and Eva Pongrácz.......................................................................................
CO2 reduction potential of renewable energy generation at water utilities
Lauri Mikkonen, Jaakko Rämö, Riitta L. Keiski and Eva Pongrácz.......................................................
Synthesis gas production by reforming of CO2-containing process gases and biogas
Esa Turpeinen, Mika Huuhtanen, Riitta L. Keiski......................................................................................
ADVANCED MATERIALS RESEARCH
CMOS-based capacitance measurements for cell adhesion sensing applied in evaluating the
cytotoxicity of nanomaterials
Niina Halonen, Timir Datta, Antti Hassinen, Somashekar Bangalore Prakash, Peter Möller,
Pamela Abshire, Elisabeth Smela, Sakari Kellokumpu and Anita Lloyd Spetz.................................
The effect of La addition on W-ZrCe oxide catalysts
Ari Väliheikki, Tanja Kolli, Mika Huuhtanen, Teuvo Maunula and Riitta L. Keiski.................................
Study of atomic oxygen adlayers on Al (100)
Giorgio Lanzani and Gian Franco Tantardini..............................................................................................
Field effect sensor devices and packaging for emissions monitoring and air quality control
Mike Andersson, Maciej Sobocinski, Jari Juuti, Anita Lloyd Spetz, Heli Jantunen......................................
Towards low-cost activated carbons as promising adsorbents
Minna Pirilä, Gerardo Cruz, Lenka Matějová, Kaisu Ainassaari, Jose Solis, Olga Šolcová
and Riitta L. Keiski..............................................................................................................................................
The effect of sulphur and water on the activity of PdPt based natural gas oxidation catalysts
Marja Kärkkäinen, Mari Honkanen, Ville Viitanen, Tanja Kolli, Mika Huuhtanen,
Kauko Kallinen, Minnamari Vippola, Toivo Lepistö, Jouko Lahtinen, Riitta L. Keiski......................
Optimisation of the composition of silica-titania support on vanadium pentoxide in
formaldehyde production
Niina Koivikko, Anass Mouammine, Satu Ojala and Riitta L. Keiski...................................................
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SKYPRO OULU CLEAN AIR CLUSTER
Science into products and production technologies: SkyPro Oulu Clean Air Cluster............. 123
Author index............................................................................................................................................................ 129
6
PREFACE
Despite dramatic progress in pollution abatement, air pollution continues to threaten human life and
wellbeing. Air pollution is cited as the main cause of lung conditions such as asthma, and the most
recent data indicate that air pollution resulted in 223,000 deaths from lung cancer in 2010. In October
2013, the specialized cancer agency of WHO, the United Nations World Health Organization announced that outdoor air pollution is the leading environmental cause of cancer deaths. According to
the International Agency for Research on Cancer (IARC), there is sufficient evidence that exposure to
outdoor air pollution causes lung cancer and provides scientific evidence on cancer-causing substances
and exposures. This is the first time that experts have classified outdoor air pollution as a cause of
cancer. The IARC has evaluated for example diesel engine exhausts, solvents, metals, and dusts.
Air pollution is defined as the contamination of the indoor or outdoor environment by any chemical,
physical or biological agent that modifies the natural characteristics of the atmosphere. The main
sources of outdoor air pollution are transportation, stationary power generation, industrial and agricultural emissions, and residential heating and cooking. Some air pollutants have also natural sources.
Pollutants of major public health concern include e.g. particulate matter, carbon monoxide, ozone,
nitrogen dioxide and sulphur dioxide. Traffic related ultrafine particles have also been found to be
responsible for adverse human health effects.
Air pollution impacts have been studied at the University of Oulu since the 1960s, when scientist
of the University embarked on the challenge to identify the reason why trees in the Oulu region
were dying. The study of pollutants continued ever since, further focusing on the analysis of paths
of pollutant transfer and exposure, impacts on human health, and intensifying in the research of air
pollution abatement. Catalytic emission control is a proven and effective way to reduce the amount
and harmfulness of emissions to air. Catalysis research at the University of Oulu has been conducted
since the 1980s, and intensified especially in the last 10 years. Collaboration with local industry has
been a key advantage, and has been done mainly within the SkyPro Oulu Clean Air Cluster under
the aegis of the Oulu Innovation Alliance. Research has culminated into advancements in materials
science, by developing ever more efficient catalysts, adsorbents and nanomaterial sensors. Material
scientists and engineers are currently seeking new and improved solutions for air pollution prevention
and control and even for the utilization of emission compounds such as CO2.
The need for new technologies for air pollution measurement, prevention, control and utilization is
pronounced. The paramount objective, also of this conference, is to raise awareness of the social,
economic and environmental facets of sustainability in all aspects of air pollution prevention. The
topics of this SkyPro Conference respond to current societal needs, and the international nature of
research is remarkable. Some 25% of co-authors in this proceedings are foreign collaborators from
10 countries, reaching across several continents, both the Northern and the Southern hemispheres.
Academic collaboration is also done with several Finnish universities, research institutes and universities of applied science. Through this effort, we can ensure the continued presence of the University
of Oulu on the international forefront of clean air research.
It is our goal that the University of Oulu will persist in its effort to advance clean air research and
development, in active collaboration with industry as well as with national and international academic
bodies, in order to provide solutions to challenges of national, European and global significance.
Lauri Lajunen
Rector, University of Oulu
INTRODUCTION
The aim of the 2 SkyPro Conference is to convene scientists at the University of Oulu working in
the field of clean air research and companies that have interests in the topic area. The aim is also
to deliver the most recent knowledge generated by the research groups and to act as a forum for
interdisciplinary science communication. The Conference is the second conference in clean air research organized by the SkyPro Oulu Clean Air Cluster. The three focus areas of the Conference are
Air pollution prevention and control, CO2 minimization and utilization (carbon capture and storage
(CCS) and utilization (CCU)) and Advanced materials research. The one-day programme includes
a plenary speech given by Dr. Toni Kinnunen from Dinex Ecocat and three key-note speeches given
by esteemed scientists of the field. In addition, the programme contains ten oral presentations and a
poster session. The Conference provides an open forum to encourage doctoral students and young
doctors to present their current research findings and to network with each other. It also serves as
a forum for industry-academia collaboration. In tandem with the academic contributions, the Conference gives companies in the field of clean air an occasion to present and exhibit their products.
nd
This proceedings book contains 26 abstracts given by 82 authors. Clean air research is conducted
actively for example in the Laboratories of Mass and Heat Transfer and Process Metallurgy, in the
Thule Institute, in the Laboratories of Microelectronics and Materials Physics and the Department
of Biochemistry. Active collaboration is done with other Finnish Academic Institutes, namely with
Aalto University, the Universities of Eastern Finland and Vaasa, Tampere University of Technology,
Turku University of Applied Science, the National Institute of Health and Welfare; but also with
companies such as with Dinex Ecocat Oy. Among the authors, there are also scientists coming from
other countries. The list of countries is extensive, collaborating authors come from Brazil, China,
Czech Republic, Germany, France, Italy, Morocco, Peru, Sweden and the USA. Clean air is truly a
global concern and thus needs concerted actions.
I would like to express my sincere thanks to the members of the Organizing Committee of this conference. Special thanks to Dr. Satu Pitkäaho, Doc. Eva Pongrácz and Lic.Tech. Jenni Ylä-Mella, whose
valuable contribution led to the successful outcome of the Conference. M.A. Heidi Pruikkonen is
warmly thanked for the editorial work of the Conference proceedings.
The Conference was organized within the SkyProSem project, funded by the European Regional
Development Fund, and the Centre for Environment and Energy at the University of Oulu. I thank
the steering committee members of the SkyProSem project for their collaboration and support.
I also thank the Environmental Technology Development Programme, which contributed to the
organization of both SkyPro Conferences.
Finally, thanks are due to all the participants for making the Conference a fruitful event.
Oulu, October 31st, 2013
Riitta Keiski
Professor, Responsible Leader of the SkyProSem project and
Program Director of the SkyPro Oulu Clean Air Cluster
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SkyProSem project 2012-2014
Responsible Leader Riitta L. Keiski
Coordinator Satu Pitkäaho
Steering group (member / deputy member):
c. Toni Kinnunen / Kauko Kanniainen,Dinex Ecocat
vc. Markku Illikainen / Katri Päivärinta, Rusko Waste Centre
Ilkka Laakso / Sami Tiuraniemi, Stora Enso
Pirjo Koskiniemi / Irja Ruokamo, Business Oulu
Eva Pongrácz / Jenni Ylä-Mella, Thule Institute, NorTech Oulu
Reijo Silvonen
SkyPro 2 Conference organizing committee:
Prof. Riitta L. Keiski, University of Oulu
Dr. Satu Pitkäaho, University of Oulu
Doc. Eva Pongrácz, University of Oulu, NorTech Oulu
Lic. Tech. Jenni Ylä-Mella, University of Oulu, NorTech Oulu
PROGRAMME
2 SkyPro Conference, November 12th 2013, University of Oulu, Environmental Sciences Building
nd
8.30–9.00
Registration and coffee
9.00–10.00
9.00
9.15
OPENING OF THE CONFERENCE
Welcome notes from Prof. Riitta L. Keiski
Plenary Lecture: Air quality concerns and technologies for
improvement. Dr. Toni Kinnunen, Dinex Ecocat Oy
10.00–11.30 SESSION 1: Pollution prevention and control
Chair: Doc. Mika Huuhtanen
10.00
Keynote 1: Catalytic emission control studies in the Mass and
Heat Transfer Process Laboratory at the University of Oulu
10.30
New knowledge for the industrial CVOC emission abatement
10.50
The chemical composition and alveolar deposition of particles
from an off-road diesel engine
11.10
Renewable hydrogen from ethanol: Reforming at low
temperatures over Ni supported catalysts
Prof. Riitta L. Keiski
Satu Pitkäaho
Kati Oravisjärvi
Prem Kumar Seelam
11.30–13.00 Lunch and poster session
13.00–14.30 SESSION 2: CO2 minimization and utilization
Chair: Lic.Sc. (Tech.) Ritva Isomäki
13.00
Keynote 2: Switchable ionic liquids in biorefining and acid gas
capture
13.30
Decarbonization of Europe by 2050: Motivation for Smart Energy
Network development
13.50
Via CO2 photoreduction over nanocrystalline TiO2 towards
valuable products
14.10
CO2 emission mitigation in ironmaking with biomass – Replacement
of coal with biomass in coke production
Prof. Jyri-Pekka Mikkola
Eva Pongrácz
Lenka Matějová
Hannu Suopajärvi
14.30–15.00 Coffee and poster session
15.00–17.00 SESSION 3: Advanced materials research
Chair: Dr. Tanja Kolli
15.00
Keynote 3: Molecular dynamics simulation of the solid-state
topochemical polymerization of S2N2
15.30
CMOS-based capitance measurements for cell adhesion sensing
applied in evaluating the cotoxicity of nanomaterials
15.50
16.10
16.30
Field effect sensor devices and Packaging for emissions monitoring
and air quality control
16.50
Closing words: Dr. Satu Pitkäaho
17.00-19.00 Evening reception hosted by SkyPro Oulu Clean Air Cluster
Prof. Risto Laitinen
Niina Halonen
Ari Väliheikki
Giorgio Lanzani
Mike Andersson
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Catalytic emission control studies in the Mass and Heat
Transfer Process Laboratory at the University of Oulu
Riitta L. Keiski*, Mika Huuhtanen, Tanja Kolli, Kati Oravisjärvi,
Marja Kärkkäinen, Mari Pietikäinen, Anna Valtanen and Ari Väliheikki
University of Oulu, Department of Process and Environmental Engineering,
Mass and Heat Transfer Process Laboratory, P.O.Box 4300, FI-90014 University of Oulu
1 Introduction
Emissions both from stationary and mobile sources are causing many environmental problems. For
instance, in the energy production the main harmful emissions are nitrogen oxides (NOx), sulphur
oxides (SOx), particulate matter (PM), unburned hydrocarbons, CO and carbon dioxide (CO2). These
emissions are controlled by tightening legislation, controlling the process conditions and also by using
catalysts to mitigate the emissions. In the Mass and Heat Transfer Process Laboratory (MHTPL), the
emission control research work by using catalysis has been done over a decade. In this overview,
examples of the research done in catalytic air pollution control in the MHTPL are presented.
2 Objectives of the research
In the MHTPL many research projects dealing with the emission control of flue and exhaust gases have
been done. In the stationary sources NOx emissions abatement has been studied by selective catalytic
reduction (SCR) using ammonia (NH3), hydrocarbons (HCs), hydrogen (H2) and ethanol (EtOH)
as reductants (e.g. in Avila et al. 2010a and 2010b, Huhtala 2011, Huuhtanen et al. 2011, Pietikäinen
et al. 2010). The oxidation and reduction reactions of unburned HCs, carbon monoxide (CO), and
NOx emissions have been studied in mobile sources using three-way catalysts (TWC) (Kolli 2006),
diesel oxidation catalysts (DOCs) and natural gas oxidation (NGO) (Honkanen et al. 2013). The
role of particulates on human health has been studied as well (Oravisjärvi 2013). To understand the
behaviour of a catalyst it is important to find out the basic HC and CO oxidation and NOx reduction
reactions as well as to determine the reaction kinetics on the catalyst surface (Huuhtanen 2006).
The role of thermal deactivation (Lassi 2003) as well as catalyst poisoning by exhaust gas impurities
such as sulphur (S) or biomass based e.g. potassium (K), phosphorus (P) and calcium (Ca) has been
studied widely by the research group (Avila et al. 2011, Kolli et al. 2009, 2010 and 2011, Kröger 2007,
Kärkkäinen et al. 2013, Väliheikki et al. 2013 and 2012, Väliheikki 2011).
3 Results
Different kind of catalyst samples have been studied both in the metallic monolith and powder
forms. To find out the effect of deactivation, the catalysts have been treated using laboratory scale
procedures. Accelerated deactivation methods have been developed for these studies. The catalysts
from the laboratory scale deactivation procedures and samples received from the real, used catalyst
converters have been compared to each other. The fresh and poisoned catalysts have been studied
in the laboratory scale activity tests (Figure 1a) with model gas compositions. In addition, the catalyst materials have been characterized by surface studies using electron microscopy (FESEM-EDX,
EFTEM), surface studies and reaction mechanisms (in situ DRIFT, TPD), specific surface area, pore
volume and size (BET, BJH), dispersion (chemisorption), and other characterization methods (e.g.
XRD, XPS, XRF, ICP-OES, AAS, Raman) to understand the differences observed in the studied
samples. Most of the equipments (some examples in Figure 1) used are located in the MHTPL but
close collaboration is done with other laboratories and universities both in national and international
*Corresponding author, E-mail: riitta.keiski@oulu.fi
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levels. In most of the cases catalyst deactivation was found to have a significant influence on the catalyst activity. Structural changes by thermal deactivation were found to cause permanent activity loss
of the catalysts. It was also detected, that some of the catalytic materials (both support and active
materials) have a significantly better resistance towards poisoning than others. In addition, poisoning
conditions (e.g. in the presence of water) have been observed to have an influence on the catalyst
activity and activity loss.
The evaluation of health effects caused by particle emissions from diesel and compressed natural gas
(CNG) fuelled engines with different exhaust after-treatment systems has been done using an ICRP66
lung deposition model (Oravisjärvi 2013) published by the International Commission on Radiological
Protection (ICRP) (ICRP 1994) and by analysing the chemical composition of particles using Scanning
Electron Microscopy (SEM-EDS). In the modelling part, the numbers of deposited particles into five
different regions of the lung have been calculated (the anterior nasal region, the main extrathoracic
region, the bronchial region, the bronchiolar region, and the alveolar interstitial region). The elements, which have been analyzed in particles using the SEM analysis, were C, Fe, Si, Ti, Na, K, Ca, Mg,
Ba, Mn, Zn, Cu, Cl, P, S and N. In addition, polyaromatic hydrocarbons (PAHs) have been analyzed
from the particle samples as they have a carcinogenic nature. Wide differences in the deposition of
particles between different human groups (e.g. adults, children, gender) and between their activity
level (e.g. sitting, heavy exercise) have been found. The chemical composition of particles varied also
a lot depending on the particle size and the used after-treatment method. These differences should
be taken into account, when possible particulate induced adverse health effects are further studied.
Figure 1 Examples of the analyzers and test reactors: a) activity test equipment, b) Micromeritics ASAP
2020 Surface analyzer, and c) Vertex 80 FT-IR equipped with PAS and DRIFT.
4 Relevance of the research
Emission control by using catalytic materials has been proven to be an effective way to reduce harmful
compounds in air during decades. Novel catalyst materials are, however, needed to fulfil the tightening regulations as well as replace hazardous materials (e.g. vanadium pentoxide, V2O5) in commercial
catalytic converters. In addition, an increased use of biofuels requires analyses how various elements
may affect the catalysts’ behaviour. It is also important to ensure that the new technologies taken into
use provide only health benefits while not producing unknown hazardous compounds.
References
Avila A, Huuhtanen M, Leino A-R, Kolli T, Kordás K and Keiski RL (2011) SO2 poisoning of noble metal
decorated carbon nanotubes. Proceedings of the Europacat X, August 28 - September 2, Glasgow,
United Kingdom, P288.
Avila A, Pietikäinen M, Huuhtanen M, Leino A-R, Kolli T, Kordás K and Keiski RL (2010a) Novel Pt/
CNT and Pd/CNT catalysts for the low temperature ammonia and ethanol assisted selective
catalytic reduction of NO. In: Clean air research at the University of Oulu, Proceedings of the
SkyPro Conference, June 3, 2010, University of Oulu, Finland, 46-49.
Avila A, Leino A-R, Huuhtanen M, Kolli T, Kordás K and Keiski RL (2010b) Novel CNT-based catalyst
materials for low temperature NH3-SCR of NO. 14th Nordic Symposium on Catalysis, Book of
Abstract, August 29 to 31, Marienlyst, Denmark, P47.
Huhtala J (2011) Preparation, characterization and activity testing for high temperature NH3-SCR
applications (in Finnish), Master’s thesis, University of Oulu, 90 p.
Honkanen M, Kärkkäinen M, Viitanen V, Jiang H, Kallinen K, Huuhtanen M, Vippola M, Lahtinen J,
Keiski RL and Lepistö T (2013) Structural characteristics of natural-gas-vehicle-aged oxidation
catalyst. Topics in Catalysis 56: 576-585.
Huuhtanen M, Huhtala J, Kolli T, Avila A, Maunula T, Kinnunen T and Keiski RL (2011) Tungsten based
catalysts for high temperature NH3-SCR of NOx. Proceedings of Europacat X, August 28 September 2, 2011, Glasgow, United Kingdom.
Huuhtanen M (2006) Zeolite catalyst in the reduction of NOx in lean automotive exhaust gas
conditions. Behaviour of catalyst in activity, DRIFT and TPD studies. Doctoral thesis, University
of Oulu, Oulu, Finland.
ICRP (1994) Human respiratory tract model for radiological protection. Annals of the ICRP, ICRP
publication 66, International Commission on Radiological Protection, Pergamon: Oxford.
Kolli T, Huuhtanen M, Kanerva T, Vippola M, Kallinen K, Kinnunen T, Lepistö T, Lahtinen J and
Keiski RL (2011) The Effect of Sulphur and Water Treatments on the Performance of Pd/ β-Zeolite
Diesel Oxidation Catalysts. Topics in Catalysis 54:1185-1189.
Kolli T, Kanerva T, Huuhtanen M, Vippola M, Kallinen K, Kinnunen T, Lepistö T, Lahtinen J and
Keiski RL (2010) The activity of Pt/Al2O3 diesel oxidation catalyst after sulphur and calcium
treatments. Catalysis Today 154 (3-4), 303-307.
Kolli T, Huuhtanen M, Hallikainen A, Kallinen K and Keiski RL (2009) The effect of sulphur on the
activity of Pd/Al2O3, Pd/CeO2, and Pd/ZrO2 diesel oxidation catalyst. Catalysis Letters 127:49-54.
Kolli T, Kanerva T, Lappalainen P, Huuhtanen M, Vippola M, Kinnunen T, Kallinen K, Lepistö T,
Lahtinen J and Keiski RL (2009) The effect of SO2 and H2O on the activity of Pd/CeO2 and
Pd/Zr-CeO2 diesel oxidation catalysts. Topics in Catalysis 52, 2025-2028.
Kolli T (2006) Pd/Al2O3 –based automotive exhaust gas catalysts. The effect of BaO and OSC
material on NOx reduction. Doctoral thesis, University of Oulu, Oulu, Finland.
Kärkkäinen M, Honkanen M, Viitanen V, Kolli T, Valtanen A, Huuhtanen M, Kallinen K, Vippola M,
Lepistö T, Lahtinen J and Keiski RL (2013) Deactivation of diesel oxidation catalysts by sulphur in
laboratory and engine-bench scale aging. Topics in Catalysis 56:672-678.
Lassi U (2003) Deactivation correlation of Pd/Rh three-way catalysts designed for EURO IV emission
limits. Doctoral thesis, University of Oulu, Oulu, Finland.
Kröger V (2007) Poisoning of automotive exhaust gas catalyst components. The role of phosphorus
in the poisoning phenomena. Doctoral thesis, University of Oulu, Oulu, Finland.
Oravisjärvi K (2013) Industry and traffic related particles and their role in human health. Doctoral
thesis, University of Oulu, Oulu, Finland.
18
Pietikäinen M, Avila A, Huuhtanen M, Kolli T, Kordás K and Keiski RL (2010) Selective catalytic
reduction of NO with ethanol over carbon nanotube supported catalyst. 14th Nordic Symposium
on Catalysis, Book of Abstract, August 29 to 31, Marienlyst, Denmark, P46.
Rahkamaa-Tolonen K, Maunula T, Lomma M, Huuhtanen M, and Keiski RL (2005) The effect of
NO2 on the activity of fresh and aged zeolite catalysts in the NH3-SCR reaction. Catalysis Today
100:217-222.
Väliheikki A (2011) NH3-SCR catalyst poisoning caused by potassium and sodium (in Finnish), Master’s
thesis, University of Oulu, 95 p.
Väliheikki A, Kolli T, Huuhtanen M, Maunula T, Kinnunen T and Keiski RL (2013) The effect of potassium and sodium biofuel impurities on the activity of Fe-ZSM-5 and W-ZSM-5 NH3-SCR catalysts,
Topics in Catalysis 56:602-610.
Väliheikki A, Kolli T, Huuhtanen M, Huhtala J, Kinnunen T and Keiski RL (2012) The influence of potassium and sodium on W-ZrCe oxide NH3-SCR catalysts. EastWest. East Meets West on Innovation
and Entrepreneurship 2012 Conference proceedings, Nicosia, Cyprus, 327-334.
New knowledge for the industrial
CVOC emission abatement
Satu Pitkäaho1*, Tuomas Nevanperä1, Lenka Matějová2,
Toni Kinnunen3, Satu Ojala1 and Riitta L. Keiski1
1
2
Institute of Chemical Process Fundamentals of the ASCR, v. v. i.,
Department of Catalysis and Reaction Engineering, Rozvojová 135, CZ-165 02 Prague
3
Dinex Ecocat Oy, Typpitie 1, FI-90650 OULU
1 Introduction
Volatile organic compounds (VOCs) are commonly present in the atmosphere at ground level in all
urban and industrial areas. Chlorinated VOCs (CVOCs) are widely used in industry as solvents, dry
cleaning agents, degreasing agents, and intermediates in the production of plastics, synthetic resins
and pharmaceuticals (Manahan 1991, Koyer-Golkowska et al. 2004). Numerous CVOCs are directly
harmful to health and the environment as carcinogens, mutagens and toxins. After chemical reactions,
CVOCs cause a number of indirect pollution problems such as ozone and smog formation in the
troposphere and depletion of the ozone layer in the stratosphere. The most persistent compounds
can lead to biological accumulation, causing toxic CVOC levels in foodstuffs (Derwent 1995, Manahan
1991, Moretti 2001). The global warming potential (GWP) of 100 years for CVOCs ranges from 10
to 1800 (IPCC 2001). Because of their harmful properties, the release of CVOCs into the environment is controlled by increasingly stringent regulations setting high demands for CVOC abatement
systems. Low temperature catalytic oxidation is a viable technology to economically destroy these
often refractory emissions.
The main objective of this study was to increase knowledge of the key properties of the catalysts to
be developed and the reaction conditions to be utilised in the catalytic abatement unit in the oxidation
of emission streams containing CVOCs, especially dichloromethane (DCM) and perchloroethylene
(PCE).
3 Results
In this study, a total of 33 different metallic monolith catalysts were studied at the laboratory scale in
CVOC oxidation. Catalysts were divided into three entities: industrial, CVOC and research catalysts.
ICP-OES, physisorption, chemisorption, XRD, UV-vis DRS, isotopic oxygen exchange, IC, NH3-TPD,
H2-TPR and FESEM-EDS were utilised for catalysts characterisation.
3.1 Industrial catalysts
The screening of the industrial catalysts proved that there are highly active and selective catalysts for
the total oxidation of CVOCs. The addition of vanadium on the catalyst was seen to improve the
activity and selectivity of the studied catalysts over the oxidation of both model compounds, DCM
and PCE (Pitkäaho et al. 2011a).
3.2 CVOC catalysts
Based on the screening of the industrial catalysts, a set of vanadium-doped CVOC catalysts were developed by the catalysts’ manufacturer to be installed into the industrial incinerator treating emission
*Corresponding author, E-mail: satu.pitkaaho@oulu.fi
20
stream containing CVOCs. The study with the CVOC catalysts in the laboratory and industry showed
that the laboratory scale tests corresponded well to the DCM oxidation results in industry. With
PCE, the conversions measured in industry were always higher than that achieved in the laboratory,
proving that operating conditions and the catalytic incinerator itself can have a significant effect on the
abatement efficiency. The catalysts operating in industry showed no decrease in their activity after
23 months in operation, demonstrating that the developed catalysts were resistant in the demanding operating conditions caused by CVOCs present in the emission stream (Pitkäaho et al. 2011b).
3.3 Research catalysts
To advance the development of even more efficient and environmentally sound catalysts for the
CVOC abatement, research catalysts were studied in the oxidation of DCM and PCE. Before starting
the tests, different operating conditions were tested at the laboratory scale in the DCM oxidation.
The most pronounced effect on the DCM conversion and on the HCl yield (the desired chlorinated
product) was caused by GHSV, followed by the DCM concentration and then the water amount in
the feed stream. The influence of water as a hydrogen source, ensuring the formation of HCl and
suppressing the unwanted by-product formation, was confirmed and the optimum water feed was
set to be 1.5 wt.% with both model CVOCs (Pitkäaho et al. 2012a, Pitkäaho et al. 2013).
Tests over the research catalysts showed that the addition of ceria and/or platinum into the catalyst
strongly enhanced the selectivity towards CO2 and decreased the formation of detected by-products
(CH3Cl, CH2O and CO). Among all the 15 research catalysts tested in DCM oxidation, Pt/Al2O3 was
found to be the most active and selective towards HCl. The results showed that high acidity correlate
well with the catalysts’ activity. The increase in the reducibility was also seen to correlate well with
the activity, but in a way that high acidity together with increased reducibility led to a highly active
and selective catalyst (see Figure 1) (Pitkäaho et al. 2013, Pitkäaho 2013).
Figure 1 Relationship between a) the total acidity and b) the H2 consumption, and the T50 temperature
in the DCM oxidation (adapted from Pitkäaho et al. 2013).
The results of the PCE oxidation showed that the nature of the support strongly affected the activity and selectivity; the introduction of TiO2 or CeO2 into the Al2O3 support made these supports
superior. Of all the 15 research catalysts, the two most active and HCl selective catalysts were Pt and
Pd supported on Al2O3-CeO2. Depending on the catalysts, C2HCl3, C2H4 and CO were detected
as by-products. Over the supports (catalyst without active metal) and above T90 (90% conversion
temperature) over all the Pt, Pd and Rh catalysts, the only oxidation products detected were CO2,
CO and HCl. The total acidity was not the determining property of the catalyst. Instead, the reduc-
ibility was seen to correlate well with the activity of the catalysts, proving that the enhanced reductive
capability is the key feature of the catalyst in the PCE oxidation (see Figure 2). The by-products, even
though detected in low quantities, confirmed that the PCE oxidation in excess hydrogen proceeds via
the breakage of all chloride atoms before the breakage of the carbon-carbon double bond, following
the order of the lowest bond energy calculated with the HSC Chemistry software.
Figure 2 Relationship between (a) the total acidity and (b) H2 consumption, and the T50 temperature in
the PCE oxidation (adapted from Pitkäaho 2013).
During the ~40-hour stability tests in the laboratory in moist conditions over Pt/Al2O3 (500 ppm of
DCM at 400 °C) and Pt/Al2O3-CeO2 (500 ppm of PCE at 600 °C) no obvious change in the activity
or selectivity of the catalysts was detected. Based on carbon balance calculations no carbonaceous
species were expected on the surface of the stability tested catalysts. This was confirmed since
there was no detectable carbon on the catalysts’ surface after the tests. Instead, some chlorine was
identified on the surface of both catalysts, which at this point did not affect the catalysts’ activity or
selectivity (Pitkäaho et al. 2013, Pitkäaho et al. 2012a).
When primary methods are not feasible in emission reduction, secondary abatement methods should
be used. The main selection criteria for the technology to be utilised in VOC abatement are costs
(both investment and treatment costs), VOC concentration, vent-gas flow rate, and the required
control level, i.e., regulatory factors. Catalytic oxidation as a destructive method is preferable and
economical when mixtures of several compounds and low concentrations of halogenated VOCs are
present in the emission. Due to the tight emission limit values set for CVOCs, activity and selectivity
are the most important selection criteria for the catalysts to be utilised in their abatement. Overall,
this study showed that there are active, selective and durable catalysts for the total oxidation of
CVOCs but further research is needed, even case by case, in order to develop effective and benign
catalysts and to select proper abatement conditions for each emission stream containing CVOCs.
22
References
Derwent RG (1995) Sources, Distributions, and Fates of VOCs in the Atmosphere. In: Hester RE &
Harrison RM (eds) Volatile Organic Compounds in the Atmosphere. Bath, Bath Press: 1-15.
IPCC (2001) Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the
Third Assessment Report of the Intergovernmental Panel on Climate Change. Houghton JT,
Ding Y, Griggs DJ, Noguer M, van der Linden PJ, Dai X, Maskell K & Johnson (eds). Cambridge and
New York NY, Cambridge University Press.
Manahan SE (1991) Environmental chemistry. Chelsea MI, Lewis Publishers, 583 p.
Moretti EC (2001) Practical Solutions for Reducing Volatile Organic Compounds and Hazardous Air
Pollutants. New York NY, American Institute of Chemical Engineers (AIChE), 150 p.
Koyer-Golkowska A, Musialik-Piotrowska A & Rutkowski JD (2004) Oxidation of chlorinated
hydrocarbons over Pt-Pd-based catalyst Part 1. Chlorinated methanes. Catalysis Today 90: 133-138.
Pitkäaho S, Ojala S, Maunula T, Savimäki A, Kinnunen T & Keiski RL (2011a) Oxidation of dichloromethane and perchloroethylene as single compounds and in mixtures. Applied Catalysis B:
Environmental 102: 395-403.
Pitkäaho S, Ojala S, Kinnunen T, Silvonen R & Keiski RL (2011b) Catalytic oxidation of dichloromethane
and perchloroethylene: Laboratory and industrial scale studies. Topics in Catalysis 54: 1257-1265.
Pitkäaho S, Matějová L, Ojala S, Gaalova J & Keiski RL (2012a) Oxidation of perchloroethylene–Activity
and selectivity of Pt, Pd, Rh and V2O5 catalysts supported on Al2O3, Al2O3-TiO2 and Al2O3CeO2. Applied Catalysis B: Environmental 113-114: 150-159.
Pitkäaho S, Matějová L, Jiratova K, Ojala S & Keiski RL (2012b) Oxidation of perchloroethylene–
Activity and selectivity of Pt, Pd, Rh and V2O5 catalysts supported on Al2O3, Al2O3-TiO2 and
Al2O3-CeO2. Part 2. Applied Catalysis B: Environmental 125: 215-224.
Pitkäaho S, Nevanperä T, Matějová L, Ojala S & Keiski RL (2013) Oxidation of dichloromethane over
Pt, Pd, Rh and V2O5 catalysts supported on Al2O3, Al2O3-TiO2 and Al2O3-CeO2. Applied
Catalysis B: Environmental 138-139: 33-42.
Pitkäaho S. (2013) Catalytic oxidation of chlorinated volatile organic compounds, dichloromethane
and perchloroethylene. New knowledge for the industrial CVOC emission abatement. Doctoral dissertation, University of Oulu Graduate School; University of Oulu, Faculty of
Technology, Department of Process and Environmental Engineering. Acta Universitatis Ouluensis.
C 455, 2013 Oulu, Finland.
The chemical composition and alveolar deposition
of particles from an off-road diesel engine
Kati Oravisjärvi1*, Mari Pietikäinen1, Juhani Ruuskanen2,
Seppo Niemi3,4, Mika Laurén4, Arto Voutilainen5,6, Arja Rautio7 and Riitta L. Keiski1
Mass and Heat Transfer Process Laboratory, P.O. Box 4300, FI-90014 University of Oulu
2
University of Eastern Finland, Department of Environmental Science,
P.O. Box 1627, FI-70211 Kuopio
3
University of Vaasa, Department of Electrical Engineering and Energy Technology,
P.O. Box 700, FI-65101 Vaasa
4
Turku University of Applied Sciences, FI-20520 Turku, Joukahaisenkatu 3 A
5
Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio
6
Rocsole Ltd., FI-70211 Kuopio
7
University of Oulu, Thule Institute, Centre for Arctic Medicine,
1
1 Introduction
Fine particles have been a great concern during recent years due to their adverse health effects. A
long-term exposure to high levels of soot and small particles has been connected to a wide range of
health effects, including respiratory and cardiovascular diseases and cancer, and it has also been linked
to an increase in total mortality, cardiopulmonary mortality and respiratory morbidity (Kappos et
al. 2004, Donaldson et al. 2001, Pope et al. 2002). Hypothetical mechanisms causing harmful effects
on human health are related to the capability of the smallest particulates to penetrate deep into the
gas-exchange region of the lung and further into bloodstream and then lead to systemic inflammatory processes in the body and changes in blood coagulation (Donaldson et al. 2001, Brunekreef
and Holgate 2002). Especially, ultrafine particles provide a wide surface area for adsorption (Penn
et al. 2005). The particles themselves or the components adsorbed on particles, such as organics or
metal ions, may have an ability to generate reactive oxygen species, and thereby can cause oxidative
stress in biological systems (Donaldson et al. 2003). Especially, transition metals and PAHs contribute
to the oxidative capacity of PM (de Kok et al. 2006). The off-road engines contribute about 50% of
the total particle emissions from combustion engines. The construction engines and engines used in
agriculture and forestry are the main emitters (Burtscher 2005). The particles emitted from these
engines may be harmful for health in various working environments and off-road engine emissions
are subject to occupational exposure regulations (Maricq 2007).
Particles originating from diesel engines are known to be especially problematic. The new emission
reduction technologies for diesel engines may change the composition of engine emissions. Therefore,
it is necessary to evaluate both the changes in diesel exhaust emissions and their possible health effects. The aim of this study was twofold: Firstly, to estimate human lung exposure to diesel particles
from off-road engines and analyse the measured particles to investigate the chemical composition
of inhaled diesel particles; secondly, to investigate differences between diesel exhaust emissions
when using diesel particulate filter (DPF) or no filter or catalyst at all. Diesel exhaust particles were
measured by using an Electrical Low Pressure Impactor (ELPI) in the Internal Combustion Engine
Laboratory at Turku University of Applied Science. Size distribution, chemical composition and
structure of particles were analysed.
*Corresponding author, E-mail: kati.oravisjarvi@oulu.fi
24
3 Results
3.1 Particle measurements
Particle size distributions emitted from an off-road diesel engine (common-rail, rated power
150kW/2200rpm, AGCO Power Inc.) were measured using the ELPI measurement system (Dekati
Ltd., Finland). In Figure 1 the diesel particle size distributions at 75% load when using DPF or no filter
are shown. As expected, the number of emitted particles was significantly lower, when the DPF was
used and up to 99% of particles were removed.
Figure 1 Measured diesel particle size distributions with standard deviations at 75% load at an engine
speed of 1500 rpm [dM/dlogDp (1/cm3)]. Numbers describe the averages of particle size distribution in
undiluted exhaust gas during test runs. DPF = diesel particulate filter.
3.2 Modelling the passage of particles
The effect of measured diesel particles on human health was estimated by modelling the passage of
particles into the human respiratory system and by characterizing the chemical composition of the
particles.
In the modelling the computerized lung deposition model, ICRP 66 with an in-house script (Pietikäinen
et al. 2009; ICRP 1994) was used. An adult male was selected as the test person for the modelling. The
particle deposition probabilities into five different regions of the lung (ET1: the anterior nasal region,
ET2: the main extra thoracic region, BB: the bronchial region, bb: the bronchiolar region, and AI: the
alveolar interstitial region) were calculated under different physical activities (sitting or light exercise)
and the exposure time was set to 60 minutes. In Figure 2 the proportions of particles deposited into
the five regions of the respiratory tract are described. The most of the particles under 0.5 µm deposit
in the AI-region of the human respiratory system. In this particle size with an increasing activity level
the number of deposited particles also increases in the AI-level.
Figure 2 Proportions of particles deposited in the five regions of the respiratory tract of an adult male
during sitting (A) and light exercise (B). ET1 = anterior nose, ET2 = main extrathoracic region, BB =
bronchial region, bb = bronchiolar region, and AI = alveolar interstitial region.
In Figure 3 the differences of particle deposition in different parts of human respiratory system while
sitting and performing light exercise have been shown. From the figure it is clearly seen that most of
the diesel particles deposit to the AI-region and the lung dose is smaller with DPF
Figure 3 Amounts of deposited diesel particles in adult male’s respiratory system during sitting and light
exercise. ET1 = anterior nose, ET2 = main extrathoracic region, BB = bronchial region, bb = bronchiolar
region, and AI = alveolar interstitial region. A = Without a filter, B = diesel particulate filter
The chemical characterization of particles was made by Scanning Electron Microscopy (SEM) (Leo
Gemini 1530 with a ThermoNORAN Vantage X-ray detector) at Åbo Akademi University in Turku,
Finland. The chemical composition of particle samples was analyzed from 12 different particle sizeranges from each test run. The elements, which have been found from the analyzed particles, were
C, Fe, Si, Ti, Na, K, Ca, Mg, Ba, Mn, Zn, Cu, Cl, P, S, N and O. The elements Cu and Zn were found
only from the particles emitted from diesel engine measurements with DPF.
It is important to make sure that the new technologies provide health benefits while not producing
unknown risks for human health. Even though the DPF system removed particles efficiently and the
total number of deposited particles in the lungs was generally lower, these particles contained a large
variety of different elements compared to particles from measurements without a filter. In addition the
26
regeneration of DPF influences most probably the emissions of small particles increasingly. Therefore
the use of DPF as an after-treatment method results in both benefits and disadvantages concerning
health effects and this needs further research.
References
Brunekreef B and Holgate ST (2002) Air pollution and health (review). Lancet 360: 1233–1242
Burtscher H (2005) Physical characterization of particulate emissions from diesel engines: a review.
Journal of Aerosol Science 36: 896-932.
Donaldson K, Stone V, Clouter A, Renwick L and MacNee W (2001) Ultrafine particles. Occupational
and Environmental Medicine 58: 211–216.
Donaldson K, Stone V, Borm PJ, Jimenez LA, Gilmour PS, Schins RPF, Knaapen AM, Rahman I,
Faux SP, Brown DM and MacNee W (2003) Oxidative stress and calcium signalling in the adverse
effects of environmental particles (PM10) Free Radical Biology and Medicine 34 (11): 1369–1382
International Commission on Radiological Protection (ICRP) (1994) Human respiratory tract model
for radiological protection. Annals of the ICRP, ICRP publication 66. Pergamon, Oxford, 329 p.
Kappos AD, Bruckmann P, Eikmann T, Englert N, Heinrich U, Höppe P, Koch E, Krause GHM,
Kreyling WG, Rauchfuss K, Rombout P, Schulz-Klemp V, Thiel WR and Wichmann H-E (2004)
Health effects of particles in ambient air. International Journal of Hygiene and Environmental
Health 207: 399-497.
de Kok TMCM, Driece HAL, Hogervorst JGF and Briedé JJ (2006) Toxicological assessment of
ambient and traffic-related particulate matter: A review of recent studies. Mutation Research 613:
103-122.
Maricq MM (2007) Chemical characterization of particulate emissions from diesel engines: A review.
Journal of Aerosol Science 38: 1079-1118.
Penn A, Murphy G, Barker S, Henk W and Penn L (2005) Combustion-derived ultrafine particles
transport organic toxicants to target respiratory cells. Environmental Health Perspectives 113:
956-963.
Pietikäinen M, Oravisjärvi K, Rautio A, Voutilainen A, Ruuskanen J and Keiski RL (2009) Exposure
assessment of particulates of diesel and natural gas fuelled buses in silico. Science of Total
Environment 408: 163–168.
Pope CA, Burnett RT, Thun MJ, Calle EE, Krewski D, Ito K and Thurston GD (2002) Lung cancer,
cardiopulmonary mortality, and long-term exposure to fine particulate air pollution. Journal of the
American Medical Association 287: 1132-1141.
Renewable hydrogen from ethanol: Reforming
at low temperatures over Ni supported catalysts
Prem Kumar Seelam1*, Anne-Riikka Rautio2, Mika Huuhtanen1,
Krisztián Kordás2 and Riitta L. Keiski1
Mass and Heat Transfer Process Laboratory, Department of Process and Environmental
Engineering, P.O. Box 4300, FI-90014 University of Oulu
2
Microelectronics and Materials Physics Laboratories, Department of Electrical Engineering,
1
1 Introduction
Hydrogen is a clean energy carrier and potential fuel for the future. In order to reduce the carbon
foot print and improve the urban air quality, hydrogen powered energy devices can be a viable option (Dunn et al. 2002). Hydrogen can be used in all fuel cell types, but the purity of hydrogen gas is
important for low temperature fuel cell devices (Brouwer et al. 2010). One of the biggest challenges
in the hydrogen driven society is the efficient hydrogen production. Hydrogen can be produced by a
steam reforming (SR) process at temperatures lower than 450°C using alcohols as feedstock. Today,
ethanol is the most produced renewable bio-fuel in large volumes and it can be stored safely. Reforming of ethanol and other bio-derived materials is a more viable way to produce hydrogen for fuel cell
applications than the traditional hydrogen production routes (Navarro et al. 2007, Vaidya et al. 2006).
In this work, SR of ethanol over CNT and zeolite-based catalysts was investigated. The pristine CNTs
were purified and functionalized by pre-treatment with 70% HNO3 solution. The CNTs decorated
with metal nanoparticles were prepared by wet impregnation; complete preparation procedure has
been reported in Seelam et al. (2010). Nickel with 2, 10 and 15 wt.% nominal loadings was introduced
on CNTs. In the case of ZSM-5 zeolite (Si/Al=29), the nickel active phase was incorporated into
ZSM-5 by four methods i.e. dry impregnation (DZ5), wet impregnation (WZ5), precipitation (PZ5),
and co-precipitation (CZ5 and uncalcined CUZ5) methods. Different characterization techniques
were used to understand the physico-chemical properties of the CNT and ZSM-5 based catalysts.
The phase purity was determined by X-ray powder diffraction (XRD), and the hydrogen reducibility
behaviour by temperature programmed reduction (TPR), structural and textural properties by
transmission electron microscopy (TEM) and textural properties by N2-physisorption were studied.
The catalysts activity studies were done in a quartz reactor with powder form catalysts. In the activity tests, 100 mg of CNT and 200 mg of ZSM-5 catalyst were used. The catalysts were reduced at
350°C for 30 min under the 10% H2 /N2 flow. The reforming reaction was done between 150-450°C
with a heating rate of 15°C min-1. The products were analysed by a Gasmet™ FTIR gas analyser and
hydrogen gas by a XMTC H2 analyser.
The main objective of this work was to study the CNT and zeolite based Ni catalysts in the low
temperature (i.e. <450°C) ethanol reforming. The first part of the work was dealing with CNT based
catalysts; the effect of various Ni loadings was investigated. In the second part of the work ZSM-5
supported catalysts were prepared and tested in SRE.
*Corresponding author, E-mail: prem.seelam@oulu.fi
28
3 Results
Significant changes in the structural properties were detected over pre-treated CNTs compared to
the pristine one (Table 1). The SBET and pore volume increased during the pre-treatment procedure
as amorphous carbon and other impurities were removed and the defects and structure dislocations were created leading to the structural changes (Seelam et al. 2013). The Ni/NiO phases were
detected in the Nix /CNT (x = 2, 10, and 15 wt.%) based catalysts. The crystallite size of Ni increased
as the loading increased from 2 to 15 wt.%. Moreover, the H2 uptake during the TPR studies reveals
that the hydrogen consumption (nH2) and also the reduction temperature (Tmax) increased with the
Ni loading. The textural properties of the CNT indicate that it is mesoporous whereas the ZSM-5
catalysts are microporous in nature. The surface areas of ZSM-5 based catalysts varied between
250-380 m2g-1, and the pore volumes from 0.14 to 0.2 cm3g-1, the values being lower compared to the
Ni/CNT-based catalysts. The proton form ZSM-5 (H-ZSM-5) exhibited the highest SBET and pore
volume compared to the Ni-loaded ZSM-5 materials.
Table 1 Properties of CNT-based catalysts.
The ethanol reforming reaction was performed using Ni/CNT catalysts with different Ni loadings.
The ethanol conversion and hydrogen production increased with reaction temperature (Fig. 1).
Initially at temperatures 150-350°C, the Ni15/CNT catalyst exhibited the highest conversion and the
complete conversion of ethanol was reached at 450°C. Over the Ni10/CNT, the complete ethanol
conversion reached below 450°C. The highest hydrogen production rate was achieved over the
Ni10/CNT catalyst (Fig. 1). The reducibility and hydrogen uptake were the highest over Ni with the
amount of 10 wt.%, even though the H2 uptake over the Ni15/CNT was similar but the reduction
temperature was higher than over the Ni catalyst with 2 and 10 wt.% Ni. 10 wt.% of Ni on CNTs
was found to be the optimal loading, which was sufficient to obtain the complete ethanol conversion
with high hydrogen and low CO formation.
Figure 1 Ethanol conversion (%) and hydrogen production (vol.%) as a function of temperature over the
Ni decorated CNT-based catalysts: effect of Ni loading.
30
References
Brouwer J (2010) On the role of fuel cells and hydrogen in a more sustainable and renewable energy
future, Curr Appl Phys 10, S9-S17.
Dunn S (2002) Hydrogen futures: toward a sustainable energy system, Int J Hydrogen Energy 27:
235–264.
Navarro RM, Pena MA & Fierro JL (2007) Hydrogen production reactions from carbon feedstocks:
fossil fuels and biomass, Chem Rev 107: 3952–3991.
Seelam PK, Huuhtanen M, Sápi A, Kordás K, Szabó M, Turpeinen E and Keiski RL (2010) CNT-based
catalysts for hydrogen production by ethanol reforming, Int J Hydrogen Energy 35: 12588-12595.
Seelam PK, Rautio AR, Huuhtanen M, Turpeinen E, Kordás K, Keiski RL (2013) Low temperature
steam reforming of ethanol over advanced carbon nanotube based catalysts, Submitted to
Int J Hydrogen Energy.
Vaidya PD & Rodrigues AE (2006) Insight into steam reforming of ethanol to produce hydrogen for
fuel cells, Chem Eng J 117: 39–49.
Catalytic oxidation of dimethyl disulphide over monometallic Pt, Cu, and Au catalysts supported on γ-Al2O3, CeO2, and
CeO2-Al2O3
Tuomas Nevanperä1*, Satu Ojala1, Satu Pitkäaho1, Nicolas Bion2,
Florence Epron2 and Riitta L. Keiski1
2
Institut de Chimie des Milieux et Matériaux de Poitiers, IC2MP, University of Poitiers,
UMR 7285 CNRS, 4 rue Michel Brunet, FR-86022 Poitiers Cedex
1
1 Introduction
Sulphur containing VOCs (SVOCs) are originating especially from wood-industry, such as pulping
processes, but also chemical production, landfill sites and waste water treatment plants are emitting
SVOCs. Examples of SVOC emission compounds are methyl mercaptan (MM), dimethyl sulphide
(DMS) and dimethyl disulphide (DMDS). Due to their harmful effects, VOC emissions have been
regulated by strict EU legislation for years (1999/13/EC, 2010/75/EC).
The application of catalytic incineration to SVOC oxidation is a tempting possibility due to its high
energy and purification efficiencies, but certain aspects i.e. selectivity, activity and stability, related to
the catalysts could still to be improved (Ojala et al. 2011). A majority of the catalysts used for VOC
abatement consist of noble metals or base metal oxides. Catalysts containing noble metals, such as Pt,
Pd and Rh, can suffer from poisoning by sulphur compounds and are not directly the best candidates
for SVOC treatment (Hwang & Tai 2011). Sulphur forms stable compounds with all the transition
metals. In the case of Pt, sulphur withdraws charge from the metal affecting valence bands, which can
lead to significant changes in the catalytic properties. Interestingly, the interaction between sulphur
and Au is poor. Au shows the lowest reactivity towards sulphur among transition and noble metals
(Rodriguez 2006).
It is also known that in SVOC oxidation Pt catalysts can oxidize the desired product, i.e. SO2 further
into SO3. The formed SO3 may further react with the catalyst to form sulphides and sulphates, with
moisture to sulphuric acid that can also react with the catalyst, and in addition with the construction
materials of the incinerator (Ojala 2005). The possible replacement or additive to a Pt-based catalyst
is Cu. Cu catalysts are active in DMDS oxidation and resist sulphur to some degree (Wang & Weng
1997). Furthermore, Au catalysts have shown promising results in terms of complete conversion of
DMDS at low temperatures (Ojala et al. 2010).
In this study nine different monometallic Au, Cu and Pt catalysts were examined in catalytic oxidation
of DMDS using Cu and Pt catalysts as references. The objective was to compare the activity and
selectivity of the catalysts and in addition to study if gold would be more stable in DMDS oxidation
compared to previously tested copper and platinum (Wang & Weng 1997, Chu & Lee 1998).
*Corresponding author, E-mail: tuomas.nevanpera@oulu.fi
32
3 Results
3.1 Catalyst preparation and characterization
Three different support oxides (Al2O3, CeO2 and CeO2-Al2O3 containing 20 wt.% of CeO2) were used
in the preparation of nine monometallic catalysts. Catalysts containing 5 wt.% of copper and 1 wt.%
of Pt were prepared by wet impregnation. Deposition-precipitation with urea was used as a preparation method for catalysts containing 1 wt.% of Au. Calcination temperature was chosen according
to the application in which total conversion of DMDS is achieved at around 600°C (Ojala 2005).
All catalysts were characterized using ICP-OES, N2 physisorption, and temperature programmed
reduction in hydrogen (H2-TPR). Results from ICP-OES, specific surface area (SBET) and H2 consumption measurements are listed in Table 1.
Table 1 Properties of the investigated catalysts.
3.2 Activity, selectivity and stability
The activities of the catalysts were compared in terms of light-off tests in a quartz glass tubular reactor
working at atmospheric pressure with WHSV of 720 ggcat-1h-1. A catalyst sample (100 mg) was placed
in the reactor on top the of a quartz sand bed (400 mg) between two quartz wool plugs. Compressed
air was cleaned from carbon dioxide and water by a gas cleaning unit, and fed into the system (1
dm3min-1). The liquid DMDS was injected into a vaporizer unit, which was heated up slightly over
the boiling point of DMDS (>110°C) and the initial concentration during the experiment was set to
500 ppm. The furnace was heated from room temperature up to 600°C with a heating rate of 5°C
min-1. The analysis was done at ppm level by a multicomponent FTIR gas analyzer, Gasmet CR-2000,
equipped with a liquid nitrogen cooled MCT-detector. The compounds followed were carbon dioxide,
carbon monoxide, nitrogen monoxide, nitrogen dioxide, nitrous oxide, ammonia, sulphur dioxide,
sulphur trioxide, methane, ethane, formaldehyde, methyl mercaptan, ethyl mercaptan, dimethyl sulphide, dimethyl disulphide, diethyl sulphate, carbonyl sulphite, ethylene, ethanol, formic acid, acetic
acid, acetaldehyde, and acetone. Activity tests were conducted for all nine monometallic catalysts as
well as the corresponding supports. Each activity test was repeated at least once to verify the result.
Activity
Complete DMDS conversion was reached in the temperature range from 300°C to 600°C with
most of the catalysts (Fig. 1a). In terms of T50 values, the 5Cu/20CeO2Al2O3 catalyst showed the
best activity in DMDS oxidation followed by 5Cu/Al2O3 and 5Cu/CeO2. With 5Cu/20CeO2-Al2O3
catalyst DMDS oxidation started at around 250°C and full conversion was reached at 325°C. The
next best catalysts reaching 100% conversion were 5Cu/Al2O3 and 1Pt/Al2O3, at substantially higher
temperatures, i.e. at around 545°C and 550°C, respectively. Noteworthy, Cu containing catalysts
showed higher activity when compared to Pt and Au containing catalysts. When Au and Pt catalysts
were compared, Au catalysts oxidized DMDS better at low and intermediate temperatures. CeO2supported catalysts started adsorbing or converting DMDS already at around 170°C. Moreover,
the light-off curves over CeO2-supported catalysts were in broader temperature ranges. The CeO2
support by itself, i.e. without any additional metal on the surface, showed considerable activity. The
DMDS light-off curves for all prepared catalysts are shown in Figure 1.
Figure 1 Activity test results showing DMDS conversion and corresponding SO2 yield.
34
Selectivity
The total oxidation of DMDS is desired in order to have SO2, CO2 and water as end-products. In this
study over 100% yields for SO2 and CO2 were observed most probably due to adsorption-desorption
phenomenon (Fig. 1b). Adsorption of DMDS was seen at temperatures lower than 100°C and therefore desorption at higher temperature resulting yields higher than 100% were possible.
Over the 5Cu/20CeO2-Al2O3 catalyst excellent selectivity (90%) towards SO2 in the temperature
range of around 300-500°C and high CH2O yield from 300°C up to 410°C were observed. The 5Cu/
Al2O3 showed similar oxidation results, but slightly lower SO2 yields. Due to the considerably high
CH2O yields the selectivity towards CO2 over a Cu containing catalyst was very low. Altogether, CeO2
containing catalysts were noticed to be SO2 selective at higher temperatures and could hold the key
to avoid sulphuric acid formation. Especially 1Au/20CeO2-Al2O3 seems promising, since it gives good
selectivities towards SO2 as well as CH2O in the temperatures of 400°C to 500°C without excessive
CO formation. However, it is important to notice that when designing a catalyst for total oxidation
of SVOCs, the formation of CH2O is not beneficiary property and finally should be avoided. Best
selectivities towards CO2 were achieved over Pt containing catalysts, which gave yields ranging from
approximately 50% to 100% in the temperature range from roughly 400°C to 600°C.
Based on the H2-TPR results it seems that the easy reducibility of the catalyst has an essential role in
the catalytic performance, since all the catalysts that had substantial hydrogen consumption during
the TPR test showed good performance in the oxidation of DMDS, namely the Cu containing catalysts. In the same way, addition of CeO2 improved this desired property of the catalyst in all cases.
Stability
According to the objectives of this study, the 1Au/20CeO2-Al2O3 catalyst was selected for the >40
h stability test at constant temperature of 475°C, since CeO2 containing catalysts showed good selectivity towards SO2 formation at higher temperatures, especially in the case of Au loaded catalysts.
At the beginning of the stability test, the initial temperature was set based on the light-off test results
of the 1Au/20CeO2-Al2O3 catalyst where T90 was seen at 525°C. However, in isothermal conditions
at 525°C, the conversion was around 98% and therefore the temperature was decreased during the
first 30 min stepwise to correspond better to the expected 90% of conversion. The results of the
long-term stability test (41.6 h) for 1Au/20CeO2-Al2O3 catalyst are shown in Figure 2.
Figure 2 Stability of 1Au/CeO2-Al2O3 catalyst in DMDS oxidation during 41.6 h test (475°C, DMDS 500
ppm, WHSV 720 dm3gcat-1h-1).
The conversion of DMDS remained stable during the whole testing period (Fig. 2a). In the first 30
min of the experiment the temperature of the oven was waited for stabilize from 525°C down to
475°C, resulting in minor fall in DMDS conversion. Throughout the stability test, a slight decline in
CH2O formation and correspondingly a small increase in CO2 as well as CO formation were detected
(Fig. 2b). The results indicate that the Au catalyst is a selective and stable catalyst in DMDS oxidation.
However, it should be further modified to eliminate the formation of CH2O instead of CO2.
Volatile organic compounds (VOCs) are one of the main contributors causing direct (e.g. toxicity,
odor) and indirect (smog and ozone formation) air pollution. Mercaptans and dimethyl sulphides are
not extremely toxic, but they can be repulsively malodorous even at very low concentrations causing discomfort in urban areas and therefore require highly efficient treatment methods (Chu & Lee
1998). When applying catalytic oxidation for the SVOC treatment high selectivity and stability of the
catalyst are needed in order to avoid the formation of material deteriorating sulphuric acid during
the processing. This research has relevance in the mitigation of harmful malodorous greenhouse
gases produced in the industry.
References
Chu H and Lee W T (1998) The effect of sulfur poisoning of dimethyl disulfide on the catalytic
incineration over a Pt/Al2O3 catalyst. Science of The Total Environment 209(2–3): 217-224.
Council Directive 2010/75/EC of 24 November 2010 on industrial emissions (integrated pollution
prevention and control). Official Journal of the European Communities L 334: 53.
Council Directive 1999/13/EC of 11 March 1999 on the limitation of emissions of volatile organic
compounds due to the use of organic solvents in certain activities and installations. Official Journal
of the European Communities L 85: 42.
Hwang C and Tai N (2011) Vapor phase oxidation of dimethyl sulfide with ozone over ion-exchanged
zeolites. Applied Catalysis A: General 393(1–2): 251-256.
Ojala S (2005) Catalytic oxidation of volatile organic compounds and malodorous organic compounds.
Doctoral thesis. University of Oulu.
Ojala S, Mikkola J and Keiski R L (2010) Au-catalysts in the Purification of TRS Emissions. Pongrácz E,
Hyvärinen M, Pitkäaho S and Keiski R L (eds.) Clean air research at the University of Oulu,
Proceedings of the SkyPro Conference, June 3rd, 2010, University of Oulu, 50-53.
Ojala S, Pitkäaho S, Laitinen T, Koivikko N, Brahmi R, Gaálová J, Matějová L, Kucherov A,
Päivärinta S, Hirschmann C, Nevanperä T, Riihimäki M, Pirilä M and Keiski R L (2011) Catalysis in
VOC Abatement. Topics in Catalysis 54(16-18): 1224-1256.
Rodriguez J A (2006) The chemical properties of bimetallic surfaces: Importance of ensemble and
electronic effects in the adsorption of sulfur and SO2. Progress in Surface Science 81(4): 141-189.
Wang C and Weng H (1997) Al2O3-Supported Mixed-Metal Oxides for Destructive Oxidation of
(CH3)2S2. Industrial & Engineering Chemistry Research 36(7): 2537-2542.
36
Total oxidation of dimethyldisulfide
over Cu-Pt-based catalysts
Bouchra Darif1,2*, Satu Ojala1, Laurence Pirault-Roy3,
Mohammed Bensitel2, Rachid Brahmi2 and Riitta L. Keiski1
Mass and Heat Transfer Process Laboratory (MHTPL), Department of Process and
Environmental Engineering, P.O. Box 4300, FI-90014, University of Oulu
2
Laboratory of Catalysis and Corrosion of Materials (LCCM), Department of Chemistry,
Faculty of Sciences of El Jadida, University of Chouaib Doukkali, BP.20, 24000 El Jadida, Morocco
3
Institute of Chemistry of Poitiers: materials and natural resources, IC2MP-UMR, B27,
University of Poitiers, Rue Michel Brunet, BP 633, FR-86022 Poitiers Cedex
1
1 Introduction
Volatile organic compounds, VOCs, have significant environmental effects on global warming, acid precipitation, and cloud formation. Thus, to reduce the releases of VOC emissions into the atmosphere
from stationary or mobile sources, several approaches are used. The most effective one to meet
the present and the future requirements, appears to be the catalytic approach (Zieba et al. 1995).
The copper-based catalysts, which are active for VOC abatement (Lahousse et al. 1998) are also
very active for the abatement of CO (Xu et al. 2001), NOx (Kang et al. 1998) and sulphur containing
VOCs (S-VOC). They also have beneficial properties to reduce the sulphur-related deactivation of
catalysts (Liao et al. 1982).
The objective of this research is to develop catalysts to treat S-VOCs. The procedure used in this
study aims at developing of less expensive catalysts possessing with high activities and good resistance
towards deactivation by creating nanosized copper-based material that can be promoted by the addition of platinum as the second active material. The possible synergetic effect of bimetallic catalysts
is studied in DMDS oxidation.
3 Results
3.1 Characterization results
Pt based catalysts are active for DMDS oxidation and the presence of Pt may improve the performance of the Cu-based catalyst. In fact, the addition of Pt enhanced the activity of Cu-Pt/Al2O3 at
lower temperatures compared to Cu/Al2O3. In order to study the correlation between the textural
and structural properties of the prepared catalysts and their performances, we have characterized
them using several physico-chemical analysis methods namely, inductively coupled plasma (ICP)
analysis to determine the chemical composition of the catalyst, physisorption of N2 at −196°C to
analyze the surface area and the porosity, and X- ray diffraction (XRD) to identify phases and crystallite sizes. The Pt-Cu interaction was examined by temperature programmed reduction (TPR), and
transmission electron microscopy (TEM). The catalyst activity was studied by light-off tests where gas
composition was measured with a Gasmet FTIR gas analyzer, Model Cr2000. The catalyst (100 mg,
mixed with quartz sand in the mass ratio of 1:2) was packed between two quartz wool plugs into a
tubular reactor. The catalysts were tested with a model S-VOC (dimethyldisulphyde DMDS) at the
temperature range from room temperature to 600°C using the heating rate of 5°C/min.
*Corresponding author, E-mail: darif.bouchra@oulu.fi
Table 1 presents the calculated crystallite sizes, surface areas as well as the correlation between the
experimental and the theoretical loading of platinum, and copper on the prepared catalysts.
Table 1 Physico-chemical properties for the prepared supports and catalysts, the loading of metallic
active phase.
The specific surface area of the impregnated catalysts in all cases is lower than the corresponding
supports independent of the metal (Table 1). This decrease could be attributed to a change in the
structure of the support when blocking the pores by the deposited metal. The crystallite size of the
impregnated catalysts seems to stay in the same level than that of support alumina. Some decrease in
the crystallite size may be observed after 10% copper loading, and 0.3% Pt and 10% copper loading.
The resulting active metal loading of the catalysts remains relatively close to the theoretical ones,
thus, the support impregnation seems to be successful. However, a slight difference between the
theoretical and the experimental value of 0.3%Pt/Al catalyst is observed.
The following results are related to the Pt-Cu interaction, which was examined by temperature
programmed reduction (TPR). The H2-TPR profiles of the prepared support and catalysts are presented in Figure 1.
Figure 1 TPR profiles of Al2O3, Pt/ Al2O3, Cu/ Al2O3 and Pt-Cu/ Al2O3.
From the H2-TPR profiles of the supports and the catalysts, one can see that there is no reduction
peak for the Al2O3 support up to 600°C due to its high thermal stability. Neither the TPR profiles for
the Pt/ Al2O3 catalyst showed a reduction peak; maybe because of the low Pt loading. The TPR profile
for Cu/Al2O3 showed H2 uptake at 235°C. This peak is observed due to the reduction of Cu2+ species.
The Pt-Cu/Al2O3 catalyst showed a reduction peak at slightly lower temperature, at 220°C, that is
38
attributed to the reduction of Pt-Cu oxidized species. The presence of platinum lowered the reduction temperature of CuO. Reduced platinum is able to dissociate hydrogen and then atomic hydrogen
can migrate and reduce copper oxide more easily. Liao et al. (1982) observed separate and combined
Pt-Cu entities coexisting on Pt-Cu/Al2O3 catalysts; the combined entities showed preferential Cu
enrichment. According to Gauthard et al. (2003) changes in the reduction temperature, observed in
the TPR profiles of the bimetallic catalysts indicate the presence of metal-metal interaction.
In order to study the morphological and compositional information of the prepared samples, TEM
measurements were done. Fig.2-a, Fig.2-b and Fig.2-c depict the TEM measurement results of 0.3%Pt10%Cu/Al2O3, 0.3%Pt/ Al2O3 and 10%Cu/ Al2O3.
a)
b)
c)
Figure 2 TEM image of the catalyst a) 0.3%Pt-10%Cu/Al2O3, b) 0.3%Pt/Al2O3 and c) 10%Cu/Al2O3.
The TEM-EDS analysis of the Pt-Cu/Al2O3 catalyst showed no Pt distributed units on the support,
but they existed on the copper particulates, that allow considering that the formation of Pt-Cu alloy may occur on the surface of the bimetallic catalyst. After quantitative analysis of the concerned
particulates, a different loading of Pt on the Cu units was observed. The reason for that may be the
heterogeneous distribution of Pt and Cu on the surface of alumina. For the 0.3%Pt/Al2O3 catalyst, the
TEM analysis showed 2 nm as the estimated size of the Pt particulate. The same particulate size was
estimated for Cu units in the Cu/Al2O3 catalyst. The size of Cu particulates was 5 nm in the Pt-Cu/
Al2O3 catalyst, although, Pt-Cu/ Al2O3 did not display very clear Pt particle images.
3.2 Catalytic activity results
The synergetic effect of Pt and Cu was studied in terms of catalytic activity. Figure 3 presents the
light-off of DMDS oxidation over 10%Cu/ Al2O3, 0.3%Pt/ Al2O3, and 0.3%Pt-10%Cu/ Al2O3 catalysts
(DMDS 500 ppm, mcat=100 mg, RT-600°C, 5°C/min).
Figure 3 Light-off of DMDS oxidation over 10%Cu/ Al2O3, 0.3%Pt/ Al2O3, and 0.3%Pt-10%Cu/ Al2O3
catalysts (DMDS 500 ppm, mcat=100 mg, RT-600°C, 5°C /min).
It was found that the Pt addition on Cu enhances the activity of the prepared catalyst in the catalytic
oxidation of DMDS. It can be seen from Figure 3 that all tested catalysts achieved 100% conversion
of DMDS, but Pt-Cu/Al2O3 showed the best performance in DMDS oxidation in the temperature
range of 300-320°C.
This work has a scientific impact, since it brings new knowledge on the catalytic materials that work in
the presence of sulphur. It has also an applied value, since sulphur-resistance of the catalysts has been
lately coming more important issue due to the utilization of novel bio-based fuels. The deactivation
phenomena occurring during the SVOC oxidation are very similar than in the case of for example
car exhaust gas catalysis. This research topic is therefore interesting for SVOC-emitting companies
(pulp mills, water treatment plants and so on), catalyst and catalytic abatement process developers
and also to fuel, engine and vehicle developers in Finland, and also internationally.
References
Gauthard F, Epron F, Barbier J, (2003) Palladium and platinum based catalysts in the catalytic reduction
of nitrate in water: effect of copper, silver, or gold addition, Journal of Catalysis 220, 182-191.
Kang M, Park ED, Kim JM, Yie JE, (2006) Cu-Mn mixed oxides for low temperature NO reduction
with NH3, Catalysis Today 111, 236–241.
Lahousse C, Bernier A, P Grange, Delmon B, Papaefthimiou P, Ioannides T, Verykios X, (1998)
Evaluation of MnO2 as a VOC removal catalyst: comparison with a noble metal catalyst, Journal
of Catalysis 178, 214–225.
Liao PC, Carberry JJ, Fleisch TH, Wolf EE, (1982) CO oxidation activity and XPS studies of
Pt-Cu/γ–Al2O3 bimetallic catalysts, Journal of Catalysis 74, 307-316.
Xu Z, Inumaru K, Yamanaka S, (2001) Catalytic properties of metal loaded silicapillared manganese
titanate for CO oxidation, Applied Catalysis A General 210, 217–224.
Zieba A, Banaszak T, Miller R, (1995) Thermal-catalytic oxidation of waste gases, Applied Catalysis
A: General 124, 47-57.
40
Total oxidation of dichloromethane
over platinum based catalysts
Zouhair El Assal1,2,3*, Satu Ojala1, Mohammed Bensitel2,
Laurence Pirault-Roy4, Satu Pitkäaho1, Rachid Brahmi2 and Riitta L. Keiski1
University of Oulu, Department of Process and Environmental Engineering, Mass and Heat
Transfer Process Laboratory, P.O.Box 4300, FI-90014-University of Oulu
2
University of Chouaib Doukkali, Faculty of Sciences, Department of Chemistry, Laboratory of
Catalysis and Corrosion of Materials, BP.20, 24000 EL JADIDA, Morocco.
3
University of Oulu, Thule Institute, P.O.Box 7300, FI-90014-University of Oulu
4
University of Poitiers, Institute of Chemistry of Poitiers: Materials and Natural Resources (IC2MP)
CNRS: UMR 7285 – University of Poitiers, BP 633- 86022 POITIERS CEDEX France.
1
1 Introduction
A simple sol-gel method was used to prepare different oxide catalysts. The performance of the
prepared catalysts was evaluated by catalytic oxidation of dichloromethane (DCM) in the presence
of water at atmospheric pressure. Air was used as the oxidant. DCM is known as a toxic solvent
used e.g. in dry cleaning and degreasing processes, in paint strippers and removers, as a propellant in
aerosols, in manufacturing drugs, pharmaceuticals (for chemical reactions, purification and isolation
of intermediates or products), film coatings, electronics, and polyurethane foams, and as a metalcleaning agent. DCM can also be used in the decaffeination process of coffee and tea. (EPA 2011,
López-Fonseca et al. 2004, Manahan 1991)
In this study the prepared supports were Al2O3 (Yoldas 1975), TiO2, and CeO2 (El Assal et al. 2013).
Alumina and titanium oxide supports were also modified with silica in order to achieve the following supports: (Al2O3)0.95(SiO2)0.05 (AlSi5), (Al2O3)0.90(SiO2)0.10 (AlSi10), (Al2O3)0.85(SiO2)0.15 (AlSi15),
(TiO2)0.95(SiO2)0.05 (TiSi5), (TiO2)0.90(SiO2)0.10 (TiSi10) and (TiO2)0.85(SiO2)0.15 (TiSi15). The catalysts
were obtained by impregnation using H2PtCl6•6H2O as the precursor to add 1wt-% of Pt on the
support calcined at 500°C. The samples were characterised by TGA-DTA, XRD, TEM, ICP and
physisorption of N2. Acidity of the catalyst surface was studied by the desorption of pyridine at different temperature that was followed by NEXUS FT-IR analyser.
The main aim of the research was to synthesize catalysts, which are highly active and selective in
catalytic oxidation of chlorinated organic compounds. Moreover, the low cost and long life time are
the desired and demanded properties of the catalysts for industrial applications. To achieve the main
aim, several catalytic materials with different physico-chemical properties were developed, characterized and tested in DCM oxidation.
3 Results
3.1 Characterisation
TGA-DTA results suggested that the desired supports were achieved at 500°C, and this temperature
was chosen for catalysts’ calcination. These results were further confirmed by XRD analysis. XRD
analysis showed also the existence of amorphous phase in addition to the crystalline phases (γ-Al2O3,
anatase (TiO2), cerianite (CeO2) and periclase (MgO)). In the case of AlSix and TiSix (x= 0, 5, 10
and 15) supports calcined at 500°C, the SiO2 phase did not appear, only γ-Al2O3 and anatase were
*Corresponding author, E-mail: zouhair.elassal@oulu.fi
observed in the samples. Additionally, the crystallite size of TiSix was influenced by the amount of
SiO2 added, but not in the case of AlSix catalysts that kept the same crystallite size. However, the
surface area of both types of catalysts was increased with increasing the SiO2 loading. The surface
area of catalysts (except AlSix) was in agreement with the crystallite size determined by XRD (surface
area increased with decreasing of the crystallite size). Pt was obtained as small nano-particles (less
than 5 nm except for TiO2 where the particle size was more than 5 nm). This result was obtained
by TEM analysis.
The pyridine adsorption-desorption showed only the presence of the Lewis acid sites on the different supports and catalysts. Their quantities were calculated by using band at 1450 cm-1 (Scire et al.
1998) and the extinction coefficient used previously for powder by Guisnet et al. (1997) (Figure 1).
The quantity of Lewis acid sites was independent on the sample’s surface area.
Figure 1 Evolution of the Lewis acidity amount of catalysts.
3.2 Activity tests
DCM oxidation experiments were carried out in a fixed-bed continuous flow reactor operating under
atmospheric pressure in the temperature range of 100-500°C with 5°Cmin-1 as the heating rate.
The inlet concentration of DCM was 500 ppm in air with the total flow of 1 l min-1. The experiments
were done in the presence of 1.5 vol-% of water in order to increase the selectivity towards HCl. The
analysis was done with Gasmet DX-4000N FTIR gas analyser (Pitkäaho et al. 2013).
The DCM conversion over catalysts with unmodified supports (i.e. the catalysts with no silica modification) was more than 90% except over Pt/MgO and MgO. The T90 (temperature needed to reach
90% of DCM conversion) order of the catalysts starting with the lowest value was as follows: PtAl2O3
< Al2O3 < PtTiO2 < TiO2 < CeO2 < PtCeO2 (Figure 2). The most significant influence of impregnation of Pt was observed in the formation of HCl as the desired end-product and also in decreasing
and/or disappearing of the CHCl3, CO and CH2O that were observed as the by-products when
the oxidation was done over the corresponding supports. The HCl yields followed the same order
that was found for the DCM conversions (Fig. 3). Also the catalyst modified with silica, i.e. PtAlSix
and PtTiSix supported catalysts showed high activity and selectivity, the one containing 10 mol-% of
SiO2 being the most active in the DCM oxidation. However, the HCl yields were the highest over
Pt/AlSi10 and Pt/TiSi15.
42
Figure 2 The activity of prepared samples in DCM oxidation (DCM 500 ppm, H2O 1.5 wt-%, GHSV 143
793 h-1, mcat = 400 mg, 5°C/min and 1.02 l/min of air).
Figure 3 Formation of HCl in the DCM oxidation over Pt/AlSix catalysts (same conditions as in Figure 2).
A good correlation between the acidity of the support and activity during DCM oxidation was
evidenced in this study. Moreover, the addition of Pt influenced the selectivity of the catalysts. The
acidity is a factor important for DCM oxidation in our study, which is in agreement with the study
done by Pinard et al. (2004).
Catalytic incineration is one of the applicable methods to efficiently and economically destroy VOC
streams containing chlorinated solvents (CVOCs). Due to tight emission limit values set to these
harmful and often toxic emissions, further research is needed in order to develop active and selective, but also inexpensive and durable catalysts to be utilised in industrial VOC abatement systems.
Acknowledgements
The authors are grateful to Mr. Stephane Pronier, Mr. Jean-Dominique Comparot and Mr. Jorma
Penttinen for their help during the characterization of catalysts and supports. The work was done
with financial support of PHC Volubilis and Thule Institute of the University of Oulu.
References
El Assal, Z, Pitkäaho S, Ojala S, Maache R, Bensitel M, Pirault-Roy L, Brahmi R, and Keiski RL
(2013) Total oxidation of dichloromethane over metal oxide catalysts. Topics in Catalysis 56:
679–687.
EPA (2011) Toxicological Review Of Dichloromethane (Methylene Chloride), Washington, DC.
Guisnet M, Ayrault P and Datka J (1997) Acid properties of dealuminated Mordenites studied by
IR spectroscopies. 2. Concentration, acid strenght and heterogeneity of OH groups. Polish Journal
of Chemistry 71: 1455–1461.
López-Fonseca R, Gutiérrez-Ortiz J and González-Velasco J (2004) Catalytic combustion of chlorinated hydrocarbons over H-BETA and PdO/H-BETA zeolite catalysts. Applied Catalysis A:
General 271(1-2): 39–46.
Manahan SE (1991) Environmental Chemistry, Fifth edit., Lewis Publishers, Michigan.
Pinard L, Mijoin J, Ayrault P, Canaff C, Magnoux P (2004). On the mechanism of the catalytic
destruction of dichloromethane over Pt zeolite catalysts. Applied Catalysis B: Environmental,
51: 1–8.
Pitkäaho S, Nevaperä T, Matějová L, Ojala S and Keiski RL (2013) Oxidation of dichloromethane over Pt, Pd, Rh, and V2O5 catalysts supported on Al2O3, Al2O3 –TiO2 and Al2O3 –CeO2.
Applied Catalysis B: Environmental 138-139: 33-42.
Scire S, Crisafulli C, Maggiore R, Minicò S and Galvagno S (1998). Effect of the acid–base properties of Pd–Ca/Al2O3 catalysts on the selective hydrogenation of phenol to cyclohexanone: FT-IR
and TPD characterization. Applied Surface Science 136: 311–320.
Yoldas BE (1975) Alumina gels that form porous transparent AI2O3. Journal of Materials Science
10: 1856–1860
44
Dichloromethane oxidation over noble metals
supported TiO2-based catalysts
Lenka Matějová1*, Satu Pitkäaho2, Jana Kukutschová1 and Riitta L. Keiski2
Nanotechnology Centre, VŠB-Technical University of Ostrava,
17. listopadu 15/2172, CZ-708 33 Ostrava
2
Transfer Process Laboratory, P.O.Box 4300, FI-90014 University of Oulu
1
1 Introduction
Dichloromethane (DCM) belongs among three most commonly used chlorinated solvents in Europe
(Euro Chlor, http://www.eurochlor.org) and it is emitted into air mostly as a part of emissions from
various industrial processes (e.g. production of pharmaceutics). It acts as a skin and eye irritating agent,
repeated or long-term exposure may cause damage to the blood, heart, liver and kidney and it is supposed to be possibly carcinogenic to humans (Material Safety Data Sheet - DCM). For that reasons
more stringent regulations for the emissions of chlorinated volatile organic compounds (CVOCs)
emissions are set and more efforts are needed to reduce these dangerous emissions (Ojala et al.
2011, Thematic Strategy on Air Pollution, 2005). The abatement of emissions containing CVOCs is
much more difficult to carry out than just VOCs abatement; e.g. higher temperatures (above 450°C)
are required for total CVOCs oxidation. Catalytic oxidation represents the cost-efficient and environmentally acceptable way how to reduce CVOCs emissions (Khan & Ghoshal 2000). However,
since the emissions limits are thight, the development of highly-efficient (i.e. more selective, active
as well as durable) catalysts for the CVOCs abatement is still a matter of keen scientific interest.
Noble metals (i.e. Pt, Pd, Au) supported metal oxide catalysts have been preferred in oxidation of
low molecular weight CVOCs due to their stability and high activity (Chen et al. 1996, Corella et al.
2000, Chen et al. 2012, Matějová et al. 2012, Pitkäaho et al. 2013). On the other hand, metal oxides
(vanadia-, magnesia-, chromia- and copper(II) oxide based catalysts) are cheaper and should be more
resistant against Cl-poisoning (Padilla et al. 1999, Ma et al. 2011, El Assal et al. 2013).
Recently the mechanism of dichloromethane oxidation over Pt/γ-alumina catalysts in moist conditions has been completely revealed by Maupin et al. (2012) including the explanation of formation of
all observed reaction by-products and products (i.e. CH2O, CO, CH3Cl, HCl and CO2). It was found
out that DCM in moist conditions disproportionates over γ-alumina support via formate species into
CO, CH3Cl and HCl, and CO and CH3Cl are further oxidized over platinum and due to temperature
effects into CO2. CO can be very easily oxidized into CO2, while CH3Cl is more refractory, thus, its
complete oxidation into CO2 occurs at higher temperatures (above ~380°C). Besides that, water
indirectly intervenes in the catalytic process by regenerating alumina hydroxyl groups, thus preventing the catalyst surface against deactivation. Maupin’s et al. work extended previous observations
from Van den Brink et al. (1998) and are in agreement with observations by Pitkäaho et al. (2013).
Contrary to γ-alumina based catalysts, titania based catalysts have been significantly less investigated
in the DCM total oxidation despite of the fact that titania (TiO2) in the mixture with some other
metal oxides (e.g. ZrO2, CrOx, CuO, CeO2 etc.) and supported noble metals could be also promising
catalyst. It has been reported that besides the surface acidity, also other factors such as the reducibility,
the oxygen storage function and the increased amount of activated oxygen on the catalyst surface
together with the strong metal–support interaction are beneficial in the DCM total oxidation and
*Corresponding author, E-mail: lenka.matejova@vsb.cz, matejova@icpf.cas.cz
for the most efficient catalyst there exists a compromise between all these properties (Chen et al.
2012, Pitkäaho et al. 2013). Moreover, the DCM oxidation mechanism over titania based catalysts
has not been clarified yet. In literature, there has been even reported on the radical initiation of the
DCM oxidation on titania supported catalysts (Windavi & Zhang 1996).
Hence, in this study the TiO2-ZrO2 supports with various molar ratios of Ti:Zr was synthesized by
the sol-gel method controlled within the reverse micellar environment of nonionic surfactant Triton
X-114 in cyclohexane, using titanium(IV) isopropoxide and zirconium(IV) propoxide in propan-2-ol
as Ti and Zr sources (Krejcikova et al. 2012), in combination with the calcination at 550°C and all supports were impregnated with ~0.5 wt.% of palladium or ~1 wt.% of platinum. For comparison also
Pt/TiO2, Pd/TiO2, Pt/ZrO2 and Pd/ZrO2 catalysts were prepared. Catalysts were characterized by
nitrogen physisorption at 77K, CO chemisorption, ICP, H2-TPR and NH3-TPD techniques etc. Then,
the sets of prepared catalysts were tested in dichloromethane total oxidation at the laboratory scale
with the aid of light-off tests.
DCM oxidation was carried out in a quartz fixed-bed tubular reactor at atmospheric pressure in the
temperature range of 100–550°C with the heating rate of 5°C/min-1. The inlet concentration of DCM
in air flow of 1.05 dm3/min-1 was adjusted to 500 volume ppm. 1.5 vol.% of H2O was added during
all catalytic experiments to ensure sufficient amount of hydrogen and thus improve the selectivity
towards desired HCl. Before the start of each catalytic test the catalyst was pre-treated by heating
up in the air stream from 25°C to 550°C and cooling down to 100°C. All catalysts were tested in
initial light-off tests at the space velocity of 71 m3/kgcat−1/h−1. The gas phase analysis was performed
on the Gasmet DX-4000N FTIR gas analyzer which was calibrated to detect following chlorinated
hydrocarbons: C2Cl4, C2HCl3, CH3Cl, CH2Cl2, CHCl3, COCl2, HCl, and following oxyderivatives of
hydrocarbons: CO2, CO, CH2O, CH3OH, and C2H4. The measured spectra were analyzed with
Calcmet for Windows analysis software. The T50 and T90 temperatures, at which 50% and 90%
conversions of DCM were observed, were chosen as a measure of catalytic activity. The CO2 and
HCl yields were also evaluated.
In this study the Pt and Pd supported TiO2-ZrO2 catalysts with various Ti:Zr molar ratios were
synthesized, characterized and investigated in the total oxidation of dichloromethane in moist conditions. The aim was to reveal the best combination of noble metal (Pt versus Pd) and TiO2-ZrO2
support, resulting in the most active and selective TiO2-ZrO2 based catalyst in the DCM oxidation.
An attention was also dedicated to the suggestion of possible DCM oxidation mechanism over these
types of catalysts.
3 Results
Based on the light-off tests it is evident that both sets of Pt and Pd supported TiO2-ZrO2 based
catalysts are similarly active, however, with more noticeable differences within T50 and T90 for Pd supported TiO2-ZrO2 based catalysts (Table 1). In comparison with Pt/TiO2, Pd/TiO2 and Pd/ZrO2 the
catalytic activity of all Pt and Pd supported TiO2-ZrO2 catalysts was significantly enhanced. Concerning
the HCl selectivity in moist conditions (i.e. in the presence of 1.5 vol.% of H2O), the Pt/TiO2-ZrO2
catalysts showed generally higher maximum HCl yields (in the range of 79-91%) contrary to the Pd/
TiO2-ZrO2 catalysts which showed the maximum yields of HCl in the range of 74-88%. The DCM
total oxidation to desired CO2 and HCl occurred best within Pt catalysts for the Pt/Ti0.3Zr 0.7On and
Pt/Ti0.9Zr 0.1On catalysts, when only traces of CH2O (1 ppm) and CO (2 ppm) were detected. From
46
Pd supported catalysts the Pd/Ti0.3Zr 0.7On catalyst was the most selective one. CH3Cl or CHCl3
were not detected according to primary spectra analysis, however, regarding these compounds the
spectra must be checked/analyzed more.
Table 1 T50, T90 and the maximum HCl yields over tested Pt and Pd supported TiO2-ZrO2 based
catalysts.
Considering the strict emission limits required by EU and the harmfulness and toxicity of CVOCs to
human health and environment, the catalytic oxidation of CVOCs represents one of the most feasible
ways of their removal from emissions which is worth further keen research and catalyst development.
Acknowledgement
This work has been elaborated in the framework of the project "Opportunity for young researchers",
reg. no. CZ.1.07/2.3.00/30.0016, supported by Operational Programme Education for Competitiveness and co-financed by the European Social Fund and the state budget of the Czech Republic and
the project MPO FR-TI3/818 of Ministry of Industry and Trade of the Czech Republic. PhD student
Jaroslav Lang from Nanotechnology Centre at the VŠB-Technical University of Ostrava and Mr. Jorma
Penttinen from MHTPL at the University of Oulu are acknowledged for their help during preparation
of catalysts and chemisorption measurements, respectively.
References
Chen B, Bai C, Cook R, Wright J and Wang C (1996) Gold/cobalt oxide for oxidative destruction of
dichloromethane. Catalysis Today 30: 15–20.
Chen QY, Li N, Luo MF and Lu JQ (2012) Catalytic oxidation of dichloromethane over Pt/CeO2-Al2O3
catalysts. Applied Catalysis B: Environmental 127: 159–166.
Corella J, Toledo JM and Padilla AM (2000) On the selection of the catalyst among the commercial
platinum-based ones for total oxidation of some chlorinated hydrocarbons. Applied Catalysis B:
Environmental 27: 243–256.
Euro Chlor, http://www.eurochlor.org (accessed November 2013).
El Assal Z, Pitkäaho S, Ojala S, Maache R, Bensitel M, Pirault-Roy L, Brahmi R and Keiski RL (2013)
Total oxidation of dichloromethane over metal oxide catalysts. Topics in Catalysis 56: 679–687.
Khan FI and Ghoshal AK (2000) Removal of volatile organic compounds from polluted air. Journal of
Loss Prevention in the Process Industries 13: 527–545.
Krejcikova S, Kočí K, Obalova L, Capek L and Solcova O (2012) Preparation and characterization of
TiO2–ZrO2 mixed oxide catalysts for photocatalytic reduction of carbon dioxide, in: M.G. Bhowon,
et al. (Eds.), Chemistry for Sustainable Development, Springer ScienceCBusiness Media B.V,
http://dx.doi.org/10.1007/978-90-481-8650-124.
Ma R, Hu P, Jin L, Wang Y, Lu J and Luo M (2011) Characterization of CrOx /Al2O3 catalysts for
dichloromethane oxidation. Catalysis Today 175: 598–602.
Matějová L, Topka P, Jirátová K and Šolcová O (2012) Total oxidation of model volatile organic compounds over some commercial catalysts. Applied Catalysis A: General 443–444: 40–49.
Material Safety Data Sheet – DCM. http://feql.wsu.edu/MSDS/Dichloromethane.pdf
Ojala S, Pitkäaho S, Laitinen T, Koivikko NN, Brahmi R, Gaálová J, Matějová L, Kucherov A,
Päivärinta S, Hirschmann Ch, Nevanperä T, Riihimäki M, Pirilä M and Keiski RL (2011) Catalysis in
VOC Abatement. Topics in Catalysis 54(16-18): 1224–1256.
Padilla AM, Corella J and Toledo JM (1999) Total oxidation of some chlorinated hydrocarbons with
commercial chromia based catalysts. Applied Catalysis B: Environmental 22: 107–121.
Pitkäaho S, Nevanperä T, Matějová L, Ojala S and Keiski RL (2013) Oxidation of dichloromethane over
Pt, Pd, Rh, and V2O5 catalysts supported on Al2O3, Al2O3-TiO2 and Al2O3-CeO2. Applied
Catalysis B: Environmental 138-139: 33–42.
Thematic Strategy on Air Pollution, Communication from the Commission to the Council and The
European Parliament, Commission of the European Communities, COM (2005) 446 final,
Brussels, 2005.
Van den Brink RW, Mulder P, Louw R, Sinquin G, Petit C and Hindermann JP (1998) Catalytic oxidation of dichloromethane on γ-Al2O3: A combined flow and infrared spectroscopic study. Journal
of Catalysis 180: 153–160.
Windawi H and Zhang ZC (1996) Catalytic destruction of halogenated air toxics and the effect of
admixture with VOCs. Catalysis Today 30: 99–105.
48
Trends of polychlorinated dioxins, -furans, -biphenyls
and polybrominated diethyl ethers in bank voles
in Northern Finland
Mari Murtomaa-Hautala1*, Matti Viluksela2, Päivi Ruokojärvi2, Arja Rautio1
1
University of Oulu, The Centre for Arctic Medicine, Thule Institute, P.O. Box 7300,
National Institute for Health and Welfare, Department of Environmental Health,
P.O. Box 95, FI-70701 Kuopio
2
1 Introduction
Dioxin-like chemicals and brominated flame retardants are ubiquitous in the environment, despite
of international bans and restrictions. Chemicals may be transported over long distances instead, all
the way to the pristine areas of northern latitudes. Levels of dioxins and brominated flame retardants
have been studied in semi-domestic reindeer and wild moose in northern Finland recently, and found
that the concentrations of dioxin-like chemicals have been found rather high especially in reindeer
calves (Suutari et al. 2009, Suutari et al. 2011). However, time series indicating the trends of these
chemicals in the environment and animals, are rare for these contaminants.
The concentrations of polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs), polychlorinated
biphenyls (PCBs) and polybrominated diethyl ethers (PBDEs) were measured in liver and muscle of
bank voles (Myodes glareolus) caught from a remote area in the Finnish Lapland during 1986-2007.
The area consists of intact boreal coniferous forest with no human activities nearby. The study population was collected as part of the annual survey on population cycles of small mammals, i.e. voles and
shrews, carried out at the Värriö research station of the University of Helsinki since early 1980´s. Five
time points were selected: years 1986, 1992, 1998, 2003 and 2007.
Small mammals, like voles, are very suitable monitors for estimating contamination of terrestrial
environment. They are closely adjusted to their environment, easy to catch, have a reasonable short
life span and a territory of limited range, which make them ideal for monitoring of contamination in
specific areas.
Analyzes were performed at the Chemical Exposure Unit of the National Institute for Health and
Welfare in Finland. The laboratory is an accredited testing laboratory (No T077), accredited by Finas
according to EN ISO/IEC 17025 requirements. The scope of accreditation includes persistent organic
compounds from tissue samples.
3.1 Results
The levels of PCDD/Fs and PCBs were decreasing from 1986 until 2003 in both female and male
voles, but they tend to increase again in 2007 (Fig. 1).
*Corresponding author, E-mail: mari.murtomaa@oulu.fi
Figure 1 The levels of PCDD/Fs and dioxin-like PCBs in bank vole liver from Finnish Lapland (A), and the
trends of dioxins and PCBs emissions in European Union in 1990-2010 (B and C information from
http://www.ceip.at/webdab-emission-database/).
3.2 Results
The peak levels of the most abundant PBDE congeners (PBDEs 47, 99, 100 and 153) were measured
in 1998 and 2003 in bank voles in Värriö region. All of the analyzed tetra-, penta- and hexa-BDEs
show similar trend of increasing concentrations towards early 2000’s followed by a sudden decrease
after 2003, which can be explained by the ban of technical penta- and octa-BDEs products in 2004
in the EU and in 2005 in the USA.
50
Figure 2 The levels of the most abundant PBDEs in bank vole female (A) and male (B) liver from Finnish
Lapland in 1986-2007.
The results show that the levels of dioxin-like chemicals remain high also in rural areas in Lapland.
Although the environmental levels of contaminants have been declining since 1970’s, PCDD/Fs are still
widely found from different compartments in environment. At the moment uncontrolled combustion, including municipal waste incineration and metallurgical processes are the largest contributors
to the PCDD/Fs releases.
The concentrations of brominated flame retardants decrease and follow the restriction rules made.
Risk management actions leading to discontinued use of penta- and octa-BDE have clearly resulted
in decreasing levels of BDEs in bank voles. Lower brominated BDEs are expected to be found in
various organisms in the future even despite the ban of penta- and octa-BDEs.
References
Suutari A, Ruokojärvi P, Hallikainen A, Kiviranta H and Laaksonen S (2009) Polychlorinated
dibenzo-p-dioxins, dibenzofurans, and polychlorinated biphenyls in semi-domesticated reindeer
(Rangifer tarandus tarandus) and wild moose (Alces alces) meat in Finland. Chemosphere 75,
617-622.
Suutari A, Ruokojärvi P, Kiviranta H, Verta M, Korhonen M, Nieminen M, Laaksonen S (2011) Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs),
and polybrominated diphenyl ethers (PBDEs) in Finnish semi-domesticated reindeer (Rangifer
tarandus tarandus L.). Environ Int 37, 335-341.
52
Decarbonization of Europe by 2050:
Motivation for Smart Energy Network development
Eva Pongrácz*, Arttu Juntunen, Jean-Nicolas Louis and Antonio Caló
University of Oulu, Thule Institute, NorTech Oulu
P.O.Box 7300, FI-90014 University of Oulu
1 Introduction
The Energy Roadmap for 2050 (COM(2011) 885/2) lays down ambitious plans for the decarbonisation of Europe. By 2050, 80-95% cutting of greenhouse gas emissions below 1990 levels is envisioned.
In 2009, electricity and heat production accounted for 36.5% of total CO2 emissions in the European Union (EU) (IEA 2011). Given this current dominant share of CO2 emissions in Europe, the
transition towards a low-carbon economy implies an almost complete decarbonization of Europe's
power sector (Jägerman et al 2013). There are a variety of roadmaps on how to achieve this, including consumption-oriented approaches such as energy efficiency and behavioural changes, as well
as production oriented, as in low-carbon renewable energy generation. As periodically fluctuating
consumption (Louis et al. 2013a) meets weather-dependent renewable energy production, balancing
demand and supply is an increasingly complex challenge (Römer et al. 2012). A common approach to
tackle these challenges is smart grids, which can match fluctuating electricity generation and demand,
and ensure an economically efficient, sustainable power system with low losses and high quality and
safety (ERGEG 2010). The expression smart grid (SG) indicates a power grid that allows suppliers
and consumers to have a two-ways communication, monitoring grid conditions, such as electricity
production, consumption and distribution in real time (European Commission 2011).
The expectation that SG may contribute to reducing CO2 emissions (Quiggin et al. 2012) is based
partially on the fact that SGs allow feeding in renewable energy. Another potential of SG is to redistribute energy profile. It was found that the residential sector is the best source for demand reduction
and static peak shifting, not only because of its potential for savings, but due to regulatory support
in form of enabling programmes (Darby et al. 2012). The EU sees smart grids as an energy structure
allowing the integration of end-users (Giordano and Fully 2012), thus enhancing energy efficiency.
In order to support the 2050 decarbonization goal through smart grids, the European Technology
Platform for Smart Grids (2012) published its Strategic Research Agenda (SRA) towards 2035. The
SRA concluded that SG research must analyse electricity systems as an integrated system, enhanced
with other energy carriers such as heat and mobility demand.
This research intends to analyse some key elements of the future smart energy network (SEN). This
includes the study of building energy efficiency through optimization of the building – grid communication (Louis et al. 2013b), study the smart electricity grid in concert with heat demand provided
by district heat and bio-energy, and some other storage functions in urban contexts, such as plug-in
cars (Caló et al. 2013). Ultimately, our research intends to describe the impact of user response toward SEN and CO2 emissions and the effects on decarbonization as a whole. Based on this, we aim
at producing a roadmap and a set of policy advising instruments to facilitate and optimise the role of
end-users, in a bottom-up approach for building SEN based systems.
*Corresponding author, E-mail: eva.pongracz@oulu.fi
54
3 Results
Keeping as a reference the EU2020 targets, the 2012-2020 period marks the beginning of smart
energy distribution networks and a radically different level and type of customer involvement. At
this stage, a number of elements are amiss, such as advanced ancillary services for the support of
a largely more complex network, definition of common standards for the significant larger pool of
stakeholders and a proper integration strategy for multiple energy vectors. The following phase, 20202035, is expected to mark the transition to an optimal Smart Energy System including the elements
previously missing: full customer participation, optimal flexibility in demand and generation with free
choice of services and providers, and the achievement of a ubiquitous energy internet. Within this
framework, we analyze the future energy network development as an integral part of a sustainable
energy economy, exploring the integration of district heating networks as well as bioenergy carriers
into a smarter distributed power network.
3.1 The potential of smart energy networks in Northern Finland
Our smart grid research team has studied the potential and the adaptability of intelligent energy
network systems in Northern Finland. A hybrid micro-grid simulator (Caló 2011) and a smart building
model (Louis 2012) from the end-user’s point of view have already been developed on a MatLab platform. The main point of the simulators is to model the communication with the energy network from
the end-user’s point of view, serving as a blueprint for modelling the SEN system. Results obtained
revealed the potential of SEN in Northern Finland, owing to a number of favourable characteristics,
such as richness of natural resources, socio-cultural background and financial instruments for the
development of an advanced electricity market such as the Nord Pool Spot run power market (Caló
2011).
3.2 Integration of renewable heating into the smart energy network
The integration of renewable heating is seen vital for the decarbonization process. District heat is
typically generated in CHP plants. We aim to further study the use district heating as a storage function in SEN. Implementing storage function to the district heating network benefits the producer by
leveling out heat load variations. This further profits both the environment and the customers, when
the producer can run the power plant under steady conditions while the storage element buffers the
changes in the heat load. Steady running results in decreased environmental emissions in terms of
consumed primary fuel and more reliable functioning of the power plant. (Verda and Colella, 2011)
On the other hand, some form of storage is necessitated in a self-sufficient small-scale power system
that utilizes energy from intermittent (wind, solar) renewable sources. From the point of view of
district heating, the excess energy can be converted to heat which further could be applied e.g. for
drying biomass used in the district heat power plant. Reducing the moisture content of the biomass
increases the energy content of it, and reduces the size of the equipment required to convert the
biomass into a useful form (Liang et al. 1996).
3.3 Building up the smart energy network model, a bottom-up approach
The energy network model is based on a modular, multi layered structure (Figure 1). At the first
layer, a single urban area is considered, the energy and information flow models between building
and grid produced, and the response levels of end-users computationally tested (Louis et al. 2013A).
This means the identification of different types of peer-microgrids based on the energy consumption
profile. It also includes the description of the connection and interaction among peer-microgrids
through three interacting networks: the power network, the district heating network and the information network.
Figure 1 Schematic representation of the considered Smart Energy Network model.
At the second, urban layer, the main goal is to integrate peer-microgrids and energy generation on
different scales. Microgrids are established on the low voltage network and aim at managing production and consumption of energy locally (Louis 2011, Lopes et al. 2012). The holarchical structure allows
the de-multiplication of the energy network by creating multiple layers by which the bottom-up approach of the energy network can be tackled (Basak et al. 2011). This structure consists of looking at
energy consumption on local level (e.g. end-user) and build up profiles and decision making by going
higher in the hierarchy of the infrastructure. This approach has the advantage to build up individual
energy profiles, which are modular, thus meeting the flexibility required for shaping heterogeneous
urban areas.
The top layer is the regional level, which includes sub-urban areas and satellite rural settlements. The
aim, in this case, is also to evaluate the system sustainability and to factor in the model the size and
the complexity of the network in terms population volume and density.
The research aims at determining to what extent people can contribute to the reduction of CO2
emissions through the choices they make concerning energy usage. To answer this question, variety
of models are created to describe the functions of peer micro-grids, intelligent home automation,
integration of small-scale renewable energy production, energy storage, and heat distribution. The
models are built so that the end-user is in the centre of it. The peer microgrid infrastructure is
expected to contribute to reducing CO2 emissions, thus help reach EU decarbonization targets.
Ultimately, this work aims at drafting a vision for smart energy networks for 2035 and draft potential
pathways toward decarbonisation.
56
References
Basak P, Chowdhury S, Dey SHN and Chowdhury SP (2013) A literature review on integration of
distributed energy resources in the perspective of control, protection and stability of microgrid,”
Renewable and Sustainable Energy Reviews, vol. 16, no. 8, 5545–5556.
Caló A (2011) Assessing the potential of smart energy grids in the Northern Periphery, Master’s
thesis, University of Oulu, Department of Process and Environmental Engineering Department,96 p.
Caló A, Louis JN and Pongracz, E., (2013). The influence of electric vehicles on CO2 emissions:
Challenges on infrastructure in cold climates. In: Pitkäaho, Pruikkonen, Pongrácz and Keiski (eds.)
(2013)Clean air research at the University of Oulu, Proceedings of the 2nd SkyPro Conference.
University of Oulu,12.11.2013, pp. 81-84.
COM(2011)885/2. Communication form the Commission to the European Parliament, the Council,
the European Economic and Social Committee and the Committee of the Regions ‘Energy
roadmap 2050’.
ERGEG (2010) Position paper on smart grids. European Regulators’ Group on for Electricity and
Gas, Bruxelles .
European Commission (2011) Joint Research Centre Institute for Energy. Smart Grid Projects in
Europe: Lessons Learned and Current Developments. Joint Research Centre Reference Report.
European Technology Platform SmartGrids (2012) Smart Grids Strategic Research Agenda for
Research, Development and Demonstration needs towards 2035.
Darby S, Strömbäck J and Wilks M (2012) Potential carbon impacts of smart grid development in
six European countries. Energy Efficiency 6, 725–739.
IEA (2011) CO2 Emissions From Fuel Combustion (2011 edition) International Energy Agency.
Jägerman C, Fürsch M, Hagspiel S and Nagl Stephan (2013) Decarbonizing Europe's power sector
by 2050 — Analyzing the economic implications of alternative decarbonization pathways. Energy
Economics 40 November 2013: 622–636.
Liang T, Khan M and Meng Q (1996) Spatial and temporal effects in drying biomass for energy. Biomass
and Bioenergy, 10, pp. 353-360.
Lopes JAP, Madureira AG and Moreira CCLM (2012) A view of microgrids. WENE, 2(1): 86–103.
Louis JN (2012) Smart buildings to improve energy efficiency in the residential sector. Diploma thesis,
University of Oulu, Department of Process and Environmental Engineering, 132 p.
Louis JN, Calo A, Leiviskä K and Pongracz E (2013a) Home Automation for a sustainable living –
Modelling a detached house in Northern Finland. Proc. EEDAL’13, 1–11, Sep. 2013.
Louis JN, Caló A and Pongrácz E (2013b), Home automation to reduce CO2 emissions associated
with energy consumption of buildings. In: Pitkäaho, Pruikkonen, Pongrácz and Keiski (eds.) (2013)
Clean air research at the University of Oulu, Proceedings of the 2nd SkyPro Conference. University
of Oulu,12.11.2013, pp. 85-88.
Römer B, Reichhart P, Kranz J and Picot A (2012) The role of smart metering and decentralized
electricity storage for smart grids: The importance of positive externalities. Energy Policy 50(2012):
486-495.
Quiggin D, Cornell S, Tierney M and Buswell R (2012) Simulation and optimisation study: Towards
a decentralised microgrid, using real world fluctuation data. Energy, 41(1) : 549–559.
Verda V and Colella F (2011) Primary energy savings through thermal storage in district heating
networks. Energy, 36, pp. 4278-4286.
Via CO2 photoreduction over nanocrystalline TiO2 towards
valuable products
Lenka Matějová1,4*, Kamila Kočí2, Zdeněk Matěj5, Satu Pitkäaho6 and Lucie Obalová3
VŠB-Technical University of Ostrava, 1Nanotechnology Centre,
2
Energy Units for Utilization of non Traditional Energy Sources,
3
Institute for Environmental Technology, 17. listopadu 15/2172, CZ-708 33 Ostrava
4
Institute of Chemical Process Fundamentals of the ASCR, v. v. i.,
Department of Catalysis and Reaction Engineering, Rozvojová 135, CZ-165 02 Prague
5
Charles University in Prague, Faculty of Mathematics and Physics,
Department of Condensed Matter Physics, Ke Karlovu 5, CZ-121 16 Prague
6
Mass and Heat Transfer Process Laboratory, P.O. Box 4300, FI-90014 University of Oulu
1 Introduction
Titania (TiO2) belongs due to its excellent photochemical activity and other photo-induced phenomena to materials under keen scientific research. It has been investigated as sensing films of gas
sensors, coatings for self-cleaning and antimicrobial surfaces, an electrode material, a support for noble
metal catalysts in oxidation of VOCs in emissions, a photocatalyst in wastewater and air treatment
technologies, as a pigment or a part of ceramics. TiO2 has been also the most tested catalyst in the
photocatalytic reduction of carbon dioxide. CO2 is the main contributor to the greenhouse effect
and the global concentration of CO2 in the atmosphere is increasing mainly due to the emissions from
fossil fuel combustion. The reduction of CO2 over photocatalysts is one of the promising methods
of its removal since CO2 can be reduced to valuable compounds such as methane, ethane, methanol
etc. by its irradiation using the UV light at ambient temperature and pressure (Usubharatana et al.
2006, Kočí et al. 2008).
In general, the photocatalytic reaction can be affected by several factors such as the light absorption,
transport of photo-generated charges (electrons e- and holes h+) onto the photocatalyst surface,
recombination of e- and h+ or by mass transfer of reactants to the catalyst surface. From these points
of view, the crystallite-size as well as the agglomerate-size is a very important parameter affecting the
above mentioned steps. A good photocatalyst should have the high photon conversion efficiency.
The effect of high specific surface area of photocatalysts is still a matter of scientific discussion.
Nanosized crystallites can also possess different shape-morphology and defects in a crystallite lattice
which may contribute to different photocatalytic behavior. In literature, there have been reported
on many chemical and physico-chemical ways of titania preparation and thus the question ‘How to
synthesize TiO2 to be the most effective in the CO2 photocatalytic reduction?’ arises. Concerning only
the chemical approaches, the sol-gel method and the precipitation belong among the most feasible
methods of preparation from the application point of view.
Based on the motivation to found out the most suitable TiO2 catalyst and its microstructural and
structural parameters for the CO2 photocatalytic reduction, several TiO2 anatase powders were
synthesized by two different chemical methods according to our previous knowledge (Matějová et
al. 2010, Matějová et al. 2012) and the correlation between micro/structural and optical properties
(i.e. crystallite-size, phase composition, microstrain, specific surface area, band gap) of TiO2 and its
photocatalytic performance in the CO2 reduction by water was investigated. For comparison, the
*Corresponding author, E-mail: lenka.matejova@vsb.cz, matejova@icpf.cas.cz
58
CO2 photocatalytic reduction was also examined over the commercial TiO2 Evonic P25. The main
products of this photocatalytic process, CH4 and H2 in a gas phase, were expected according to
earlier studies (Kočí et al. 2009).
TiO2 anatase powders were prepared by (i) the sol-gel method controlled within reverse micelles
of non-ionic surfactant Triton X-114 in cyclohexane (Matějová et al. 2010) and (ii) the precipitation
method using titanium(IV) alkoxides and a dilute solution of hydrogen peroxide (Matějová et al. 2012)
in a combination with calcination at various temperatures. As a titanium source, either titanium(IV)
isopropoxide, or titanium(IV) n-butoxide (Aldrich, purity >98%) was used. More details about the
preparation and the labeling of TiO2 photocatalysts are summarized in Table 1. Commercial TiO2
Evonic P25 was delivered by Sigma-Aldrich (Prague, Czech Republic).
Table 1 Details about preparation of TiO2 powders and their labelling.
Photocatalysts were characterized by nitrogen physisorption at 77 K, powder X-ray diffraction (XRD),
diffuse reflectance spectroscopy (DRS), field emission scanning electron microscopy (FESEM) and
organic elementary analysis. Within XRD analysis the advanced MSTRUCT software (Matěj & Kužel
2009, Matěj et al. 2010), based on the free crystallographic library ObjCryst/FOX (Favre-Nicolin
ˇ
& Cerný,
2002) and implementing the WPPM method (Scardi & Leoni 2002) which combines the
Fourier modelling of diffraction line profiles (Scardi & Leoni 2001) with the Rietveld refinement of
crystal structure parameters, was applied for the refinement of micro/structural parameters.
The photocatalytic reduction of CO2 was carried out in an apparatus composed of a stirred batch
annular reactor with a suspended catalyst illuminated by the UV 8 W Hg lamp with a peak light
intensity at 254 nm (Ultra-Violet Products Inc., USA,11SC-1). The lamp was situated in the center of
the quartz tube. The shell tube was made from stainless steel. 100 mg of the catalyst powder (grain
size fraction <0.160 mm) was suspended in 100 ml of 0.2 M NaOH solution for a typical batch. Supercritical fluid-grade CO2 with a certified maximum of hydrocarbons less than 1 ppm was used as
the reactant to avoid any hydrocarbon contamination. A magnetic stirrer at the bottom agitated the
catalyst-suspended solution to prevent sedimentation of the catalyst. The temperature and pH of
the solution and the pressure of the gas phase were continuously monitored. Prior to the illumination, CO2 was bubbled with a constant flow through the stirred suspension for at least 30 min to
purge the air and to saturate the solution. The reactor was tightly closed and the CO2 pressure was
maintained at 110 kPa. Then the photocatalytic reaction was started by switching on the UV lamp.
The gas chromatograph, equipped with the flame ionization and thermal conductivity detectors, was
used for the analysis of gaseous reaction products. Several blank experiments were performed to
ensure that the hydrocarbon production was due to the photoreduction of CO2 and to eliminate the
surrounding interference (Kočí et al. 2013). The accuracy of measurements was verified by series of
repeated measurements and the relative error of product yields (µmol.g-1) of 10 % was determined.
As the influence of synthesis on micro/structural properties of TiO2 and the relationship between
micro/structural properties and the photocatalytic efficiency of TiO2 in the reduction of CO2 is still a
matter of discussion, this study deals with the preparation of nanocrystalline TiO2 anatase powders,
the refinement of their micro/structural properties and their correlation with the performance of
TiO2 in the CO2 photoreduction which leads to valuable products such as CH4 and H2 in a gas phase.
3 Results
3.1 Catalyst characterization
Results from nitrogen physisorption, advanced XRD analysis (Matěj et al. 2013) and diffuse reflectance
spectroscopy are summarized in Table 1.
Table 2 Properties of investigated TiO2 catalysts.
Median of anatase crystallite-size distribution
Weight fraction of anatase
3
Microstrain in anatase crystallites
1
2
3.2 The photocatalytic reduction of CO2
The effect of irradiation time on the formation of products in the CO2 photocatalytic reduction over
different TiO2 catalysts was investigated for a period of 0–24 h. Methane was determined as the main
product in the gas phase. Hydrogen was also detected. The observed order of yields (in μmol.g-1
of the catalyst) over all tested catalysts was: H2 > CH4. Comparison of the CH4 and H2 yields over
all examined catalysts is plotted as a function of time in Figure 1. The yields of CH4 were negligible
up to 5 h of irradiation in all cases, but after that a substantial increase of the CH4 yields occurred.
The highest yield of methane was observed for ISOP-400. The yields of H2 were under the limit of
detection during the first 8 h of irradiation for ISOP-400 and nBUT-380, for REF-450 even during
the first 16 h. Then the rapid increase of hydrogen amount took place. The deceleration of hydrogen
formation was observed after 18 h.
60
Figure 1 Dependence of methane and hydrogen yields on time over different TiO2 catalysts.
The data from the 24 h period were selected for the comparison of photocatalytic performance of
individual TiO2 catalysts because in this time the yields of all products were the highest ones and,
thus, the GC analysis was the most reliable. The yields of both main gaseous products related to
the weight of catalyst for individual TiO2 catalysts are depicted in Figure 2 (left). The photocatalytic
performance of TiO2 catalysts is decreasing in the order ISOP-400 > nBUT-380 > REF-450 > TiO2
Evonic P25. Both the best TiO2 catalysts, ISOP-400 and nBUT-380, were prepared by the precipitation method and despite of a bit different phase composition (Table 2) they possess the same band
gap 3.08 eV. They showed the highest surface areas 96 and 72 m2g-1 for nBUT-380 and ISOP-400,
respectively, which pretty correspond to their smaller and lager size of anatase crystallites (Table 2).
Thus, according to the photocatalytic results (expressed in μmol.g-1 of the catalyst) it seems that the
optimum catalyst for the CO2 photocatalytic reduction should have the anatase crystallite-size of
8–14 nm and can contain low amounts of other titania crystalline phases.
In order to assess the effect of catalysts surface area, because it is supposed to be the determining
parameter of available “active sites” (i.e. sites for the creation of e- and h+) for the reaction to take
place, the yields of both main gaseous products were expressed per 1 m2 of the catalyst surface (Figure
2, right). The trend of such expressed photocatalytic performance of TiO2 catalysts does not follow
the same trend when the yields of both main gaseous products are related to the weight of catalyst.
The ranking is following: REF-450 > ISOP-400 > nBUT-380 > TiO2 Evonic P25. This shows that the
surface area is one of important parameters, but not the determining one in the CO2 photocatalytic
reduction, and more essential role will play structural (i.e. anatase crystallite-size, presence and
character of minor crystalline phases) or microstructural (i.e. microstrain) properties. In fact, these
parameters all together influence also the band gap.
Figure 2 The yields of gaseous products in the CO2 photocatalytic reduction related to
the weight (left) and the specific surface area (right) of TiO2 catalysts after 24 h irradiation.
Considering the increasing concentration of CO2 in the atmosphere due to human activities (mainly by
emissions from fossil fuel combustion), CO2 as a greenhouse gas represents a serious environmental
problem which must be solved. Since CO2 is rather an inert and stable compound, its reduction is
difficult to carry out. The reduction of CO2 using photocatalysts belongs among the most promising
methods because CO2 can be reduced by the UV light at room temperature and atmospheric pressure, moreover, to valuable products.
Acknowledgement
This work was supported by the project "Opportunity for young researchers", reg. no.
CZ.1.07/2.3.00/30.0016, supported by Operational Programme Education for Competitiveness
and co-financed by the European Social Fund and the state budget of the Czech Republic, the EU
project "ENET", reg. no. CZ.1.05/2.1.00/03.0069, and by the Grant Agency of the Czech Republic
(project No. P108/11/1539).
References
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Favre-Nicolin V and Cerný
R (2002) FOX, 'free objects for crystallography': a modular approach to
ab initio structure determination from powder diffraction. Journal of Applied Crystalography
35: 734-743.
Kočí K, Obalová L, and Lacný Z (2008) Photocatalytic reduction of CO2 over TiO2 based catalysts
- Review. Chemical Papers 62: 1-9.
Kočí K, Obalová L, Matějová L, Plachá D, Lacný Z, Jirkovský J and Šolcová O (2009) Effect of TiO2
particle size on photocatalytic reduction of CO2. Applied Catalysis B: Environmental 89:
494-502.
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Kočí K, Matějová L, Reli M, Capek
L, Matějka V and Obalová L (2013) Sol-gel derived Pd supported
TiO2-(ZrO2) photocatalysts; their examination in photocatalytic reduction of carbon dioxide.
Catalysis Today, accepted.
Matěj Z and Kužel R (2009) MStruct - program/library for MicroStructure analysis by powder
diffraction. <http://www.xray.cz/mstruct/> (September, 2013).
62
Matěj Z, Kužel R and Nichtová L (2010) XRD total pattern fitting applied to study of microstructure
of TiO2 films. Powder Diffraction 25: 125-131.
Matěj Z, Matějová L and Kužel R (2013) XRD analysis of nanocrystalline anatase powders prepared
by various chemical routes: correlations between micro-structure and crystal structure parameters. Powder Diffraction, in press.
Matějová L, Cajthaml T, Matěj Z, Benada O, Klusoň P and Šolcová O (2010) Super/subcritical fluid
extractions for preparation of the crystalline titania. The Journal of Supercritical Fluids 52:
215–221.
Matějová L, Matěj Z and Šolcová O (2012) A facile synthesis of well-defined titania nanocrystallites:
Study on their growth, morphology and surface properties. Microporous and Mesoporous
Materials 154: 187-195.
Scardi P and Leoni M (2001) Diffraction line profiles from polydisperse crystalline systems. Acta
Crystalographica A 57: 604-613.
Scardi P and Leoni M (2002) Whole powder pattern modelling. Acta Crystalographica A 58:
190-200.
Usubharatana P, McMartin D, Veawab A and Tontiwachwuthikul P (2006) Photocatalytic proces for
CO2 emission reduction from industrial flue gas stream. Indian Engineering Chemistry Research
45: 2558-2568.
CO2 emission mitigation in ironmaking with biomass –
Replacement of coal with biomass in coke production
Hannu Suopajärvi*, Juho Haapakangas and Timo Fabritius
Laboratory of Process Metallurgy
1 Introduction
Metallurgical coke charged from the top of the furnace is the most important energy source and
reducing agent in the blast furnace. In modern European blast furnaces operating near thermodynamic limits, approximately 310–360 kg coke per ton of hot metal is consumed. Coke is produced
in coke ovens, in which 1.33 tons of coking coal is needed to produce one ton of metallurgical coke.
In Finland, some 900 000 tons of metallurgical coke is produced annually. Coke production and use
result in various particle emissions and, above all, huge fossil CO2 emissions.
It has been proposed that a small share of the coking coal could be replaced with biomass-based raw
materials (e.g. Montiano et al. 2014). One of the key features of metallurgical coke is the mechanical
strength, which has to be high due to blast furnace process features (Haapakangas et al. 2012). The
objective of this research is to evaluate how biomass addition changes the cold strength of metallurgical coke. Bio-cokes (part of the coking coal replaced with biomass) are produced in laboratory scale
and their cold strength is measured. Additionally we evaluate the CO2 emission reduction potential
in Finnish coke production based on the experimental results using a carbon footprint model.
2 Materials and methods
2.1 Raw materials
Riverside coking coal supplied by Ruukki was used in the production of reference coke (RC). Biomassbased raw materials applied in the coking experiments to replace part of the coking coal were: 1)
Mixed hardwood charcoal (MHCC) (Cfixed 79.5%), 2) Birch hardwood charcoal (BHCC) (Cfixed 75.1%),
3) Torrefied wood (TW) (Cfixed 23.3%) and 4) Russian charcoal (RCC) (Cfixed 86.7%). Particle size of
the coal was 70 wt% 0.5-1.0 mm and 30 wt% < 0.5 mm. Biomass-based raw materials were grinded
to particle size below 0.5 mm. The amount of biomass-based coal additions were 5 wt% and 10 wt%,
and the smaller fraction of the coking coal was replaced with biomass-based raw materials.
2.2 Experimental methods
Coking experiments were conducted with a laboratory scale coking battery, previously used in experiments with plastic addition to coking coal blend (Heino et al. 2012). The heating rate was 3 °C/min
and the final temperature 1200 °C. Nitrogen flow (2 l/min) was used during the heating and cooling
to avoid oxidation. Nine coke cylinders with diameter of 17 mm and height of roughly 40 mm were
produced in one coking experiment. The coke cylinders were sawn into three samples, which were
used in the cold strength test. Each formed coke sample had the height of 11 mm. Cold strength
tests were done with Gleeble 3800 thermochemical simulator, previously used in Haapakangas et
al. (2013). The cold strengths of the bio-cokes were compared to both industrial coke as well as
reference coke produced with the experimental coking battery.
*Corresponding author, E-mail: hannu.suopajarvi@oulu.fi
64
2.3 Carbon footprint model
The carbon footprint (CFP) model was developed to evaluate the CFP of torrefied wood (TW) and
charcoal (CC) produced from Finnish wood-based raw material (Suopajärvi et al. 2014). The model is
used to examine the CO2 emission mitigation potential when applying biomass-based raw materials in
coking coal blend to produce bio-cokes. CO2 emissions resulting from coke production are assumed
to be 673 kg/t coke (Gabi 5 database). Ultimately, almost all the carbon in the coke is released to
the atmosphere as CO2. With carbon content of 88%, one ton of coke produces 3.22 tons of CO2.
3 Results
This part of the paper presents the first experimental results of bio-coke properties and CO2 emission reduction potential when replacing part of the coal with biomass.
3.1 Mechanical strength of produced cokes
The cold strength of the reference coke and bio-cokes are presented in Table 1. The strength of the
reference coke was very close to the strength of industrial coke (3-5 kN) so the experimental procedure was found suitable. Amount of samples was 6 in cold strength measurements. It can be seen
that the strength of the reference coke is the highest. However, when the share of biomass-based
raw material is 5 wt%, the strength of the bio-cokes remains at reasonable level. When the share of
CC and TW is increased to 10 wt%, the cold strength of the bio-cokes deteriorates more significantly
Table 1 Cold strength of the reference coke and bio-cokes.
Our first experiments with bio-cokes suggest that 5 wt% of the coking coal could be replaced by CC
and some 3-4 wt% with TW. Similar replacement amount with CC addition has been proposed by
MacPhee et al. (2009).
3.2 Carbon footprint of charcoal and torrefied wood
CFP of charcoal and torrefied wood produced from logging residues (LR) was calculated with different
assumptions (Fig. 1). Charcoal cases: 1) LR case 1 with direct emissions from supply chain and indirect
emissions from electricity production, 2) LR case 2 as in the first case, but CO2 emissions from fertilizer production included, 3) LR case 3 as in the second case, but CO2 emissions from carbon stock
change (CSC) included with 100 year time horizon (TH). Torrefied wood cases: 1) LR case 1 with
direct emissions from supply chain and indirect emissions from electricity production, 2) LR case 2
as in the first case, but CO2 emissions from fertilizer production and carbon stock change included.
Charcoal production yields by-products that are assumed to be used in electricity production with
30% efficiency.
Figure 1 Carbon footprint of charcoal and torrefied wood.
CFP of charcoal without by-product credits, fertilizer use and carbon stock change is 214.3 kgCO2 /t
and CFP of torrefied wood is 107.4 kgCO2 /t. If indirect emissions from carbon stock change are accounted, the CO2 emissions become considerable higher. However, currently these emissions are
not taken into account in EU RED methodology and are not considered in the following calculations.
3.3 CO2 mitigation potential when using biomass raw materials in coke making
Assuming that 5 wt% CC or 3 wt% TW is used to replace coking coal, using Ruukki coking plant as a
reference, we can calculate how much fossil CO2 emissions could be reduced. Additionally, we assume
that CC replaces coking coal in 1:1 ratio and TW in 0.4:1 ratio. This is because TW has high share of
volatiles, which will, for the most part, end up in gases. CO2 emissions from reducing agent production
and use (coke, CC and TW) with and without by-product credits from biomass-based products are
presented in Fig. 1. On a life cycle basis, the reduction in fossil CO2 emissions from reducing agent
production and use could be 4.6% (6.3% with by-product credits) with CC and 1.1% with TW.
Figure 2 CO2 emissions from reducing agent production and use.
66
It seems that biomass-based CC is more suitable than TW to replace coking coal in metallurgical
coke production. Bio-cokes produced with CC addition have higher cold strength and lower CFP
than with TW addition. Coke production rate in the base case is 0.9 Mtons with 1.2 Mton coal use. In
order to maintain the coke production rate at the same level, coal need is 1.140 Mtons with CC and
1.186 Mtons with TW addition. Low coal replacement ratio of TW makes its use in coke production
less attractive than use in blast furnace injection (Wiklund et al. 2013).
Preliminary results of adding biomass-based components into coking blend and resulting bio-cokes
suggest that considerable reduction in fossil CO2 emissions could be attained in ironmaking. More
research is needed to further develop the properties of bio-cokes.
References
Haapakangas J, Uusitalo J, Mattila O, Kokkonen T, Porter D, Fabritius T (2013) A Method for Evaluating
Coke Hot Strength. Steel Research International Vol.84: 65-71.
Heino J, Gornostayev S, Kokkonen T, Huttunen S, Fabritius T (2012) Waste plastic – from harmful
carbon based material to valuable raw material of metallurgical coke, coke oven gas, hydrogen,
and hydrocarbon oil. In: Carbon 2012 conf., Krakow, Poland.
MacPhee JA, Gransden JF, Giroux L and Price JT (2009) Possible CO2 mitigation via addition of
charcoal to coking coal blends. Fuel Processing Technology Vol.90(1): 16-20.
Montiano MG, Diaz-Faes E, Barriocanal C and Alvarez R (2014) Influence of biomass on metallurgical
coke quality. Fuel Vol.116:175-182.
Suopajärvi H, Pongrácz E, Fabritius T (2014) Carbon Footprint (CFP), Energy Return on Investment
(EROI) and economic evaluation of bio-based reducing agents for blast furnace ironmaking.
Manuscript, to be sent for publication in: Applied Energy.
Wiklund CM, Pettersson F and Saxén H (2013) Optimization of a Steel Plant with Multiple Blast
Furnaces Under Biomass Injection. Metallurgical and Materials Transactions B Vol.44(2):447-458.
Sustainability assessment of commercial and CO2-based
synthesis routes of Dimethyl carbonate
Paula Saavalainen1*, Eva Pongrácz2, Danielle Ballivet-Tkatchenko3 and Riitta L. Keiski1
Department of Process and Environmental Engineering, P.O. Box 4300,
FI-90014 University of Oulu
2
Thule Institute, NorTech Oulu, P.O. Box 7300, FI-90014 University of Oulu
3
Institut de Chimie Moléculaire, CNRS, Université de Bourgogne,
9 Avenue Alain-Savary, FR-21000 Dijon
1
1 Introduction
Carbonic esters are important chemicals found in many commodity applications such as organic
synthesis, perfumes, pharmaceuticals, polymers, solvents and lubricants. Organic carbonates have
a high market potential, currently limited by their hazardous production technologies, due to the
use of toxic raw materials and intermediates such as phosgene and carbon monoxide. (Delledonne
2001) Dimethyl carbonate (DMC, (CH3) 2CO3) is an important chemical intermediate. Due to its
low toxicity, rapid biodegradability and low impact on air quality, DMC has been proposed to be a
possible gasoline blending component. (Pacheco 1997, Rivetti 1996, Katrib 2002) DMC can replace
more toxic or less biodegradable additives such as Methyl tert-butyl ether (MTBE) and it is also an
outstanding oxygenate due to its very high oxygen content (Pacheco 1997). New synthesis methodologies under research and development are focused on reducing the hazards of solvents and
chemicals conventionally used. This paper reports on a research aiming at developing sustainable
processes for the production of DMC using carbon dioxide (CO2) as a raw material. Using CO2 as a
carbon feedstock has several advantages; it is non-toxic, abundant in supply, and innovative, offering
completely new ideas for production processes and even products. CO2-based reaction routes may
also lead to cleaner products of higher quality. To facilitate this goal, new, effective catalysts for DMC
syntheses are sought after, and safe, environmentally friendly reaction pathways and energy-efficient
processes are explored. However, in order to fully evaluate the sustainability all of the suggested new
process routes, there is a need for a comprehensive evaluation of the environmental, economic and
social impacts of these new routes and intermediates. This requires assessment methods capable of
evaluating the impact of these new routes at early process design stages.
This paper intends to evaluate the sustainability of novel production routes of dimethyl carbonate
(DMC) under research, using carbon dioxide (CO2) as a raw material. The paper uses the twelve
principles of Green Chemistry (Anastas & Warner 1998) in evaluating the sustainability of process
routes at an early design phase.
3 Methodology
In this assessment, an extended Green Chemistry Toolkit, based on that devised by Envirowise
(Chambers 2004) was used to assess the triple bottom line of sustainability. The Envirowise Green
Chemistry Toolkit has 5-6 questions for every of the 12 Green Chemistry (GC) principles. We have
modified the questions to be more suitable for the development of new chemical process. As well,
since the Green Chemistry Toolkit questions were considering environmental factors mainly, with
only minor considerations on economic and social aspect, questions that we felt were missing were
added. In order to have a wider consideration over the entire life-cycle of products under development, supply chain related questions were also added whenever considered reasonable. Originally,
*Corresponding author, E-mail: paula.saavalainen@oulu.fi
68
the Toolkit had two additional points considering product lifecycle and supply chain management;
however we found it prudent to maintain only the original GC principles, and the supply chain questions were merged into the existing 12 Principles.
3.1 Usage of the proposed tool
We have provided sets of questions for process designers to consider, fostering the incorporation
of all the aspects of sustainability into process designs. It is suggested that considering the issues
outlined would allow making an indicative triple bottom line assessment of new chemical processes
or products at the design phase. At this stage, we also propose to use a ‘traffic light’ rating system in
conjunction with the question list, valuing negative impacts with shades of red colours (the darker
the worse), neutral impacts with white colour, and positive impacts with shades of green colours
(the darker the better). It is expected that this strong visualization of weak points would provide
incentives for improvement strategies. This would also provide a well-defined evaluation of progress
towards meeting GC principles.
4 Results
Possible reaction routes to DMC synthesis are presented in Figure 1 and the detailed chemical equation for reaction routes are explained in Table 2.
Figure 1 Possible reaction routes for producing DMC. [11]
Table 1 Reaction routes to DMC.
Route 1:
Ammonium route
3H2 + N2  2NH3
2NH3 + CO2  CH4N2O + H2
CH4N2O + 2CH3OH  (CH3O)2CO + 2NH3
Route 2:
CO/CO2 route
2H2 + CO  CH3OH
3H2 + CO2  CH3OH + H2
CO2 + 2CH3OH  (CH3O)2CO + H2O
C2H4O + CO2  C3H4O3
C3H4O3 + CH3OH  (CH3O)2CO + C2H6O2
Route 3:
CO2 route
Route 4:
Phosgene route
Route 5:
Carbonylation route
COCl2 + 2CH3OH  C3H6O3 + 2HCl
CO + 0.5O2 + 2CH3OH  C3H6O3 + H2O
In reaction 1, urea is used as a raw material. Production of urea needs ammonium as raw material.
Urea is a common bulk chemical, but the price of urea is likely to increase due to energy costs and an
unprecedented demand. Notwithstanding, urea is rather safe to use. Ammonium is also produced as
a by-product and, in an optimal case; it could be recycled as a raw material for the urea production. In
reaction 2, fossil fuel based raw materials are used, where methanol is produced with CO and CO2 and
hydrogen. Reaction 3 uses oil refinery products and CO2 as raw material. In reaction route 4, highly
toxic phosgene is used as a raw material. Its use, therefore, provides high risks in production safety.
In reaction routes 1-3, commercial catalytic materials are under development. In route 4, no catalyst
is used and, in route 5, commercial copper catalysts are used. Catalytic materials for routes under
development should be chosen so that with the catalyst materials environmental impact is minimised,
i.e. enhancement of reaction activity and selectivity and stability of the catalyst as well as environmentally benign catalytic materials.
In reaction routes 1-3, reaction conditions such as temperature and pressure, are yet unresolved as
these routes are still under development; however, they are expected to be rather high. Reaction
conditions should further be developed so that temperature and pressure are optimised at a lower
level to minimize environmental impacts. Reaction routes 4-5 are using low pressure and take place
at room temperature. The environmental benefit of this is to be highlighted, when compared with
routes under research (1-3).
In reaction routes 2 and 5, only water is produced as a by-product. In route 1, ammonium is produced as a by-product. In route 3, toxic ethylene or propylene glycol is produced; however, they
are very valuable from a commercial point of view. Their possible utilization needs to be considered
already at the design phase. In reaction route 4, HCl is produced as the by-product, which needs to
be cleaned and neutralized.
Atom economy is best for the methanol-based reaction routes 2 and 5. However, it needs to be
assessed if the atom economy benefit overweighs other impacts of the reactions. Still, both of them
use carbon monoxide as a raw material and reaction route 2 also requires hydrogen, the production
of which is very energy demanding.
3.2 Sustainability assessment of the DMC reaction routes
As indicated earlier, the results have been evaluated using colour coding; deeper hues of red indicating
more severe impact. It is striking in the comparison the heavily negative assessment of the phosgene
–based route. This actually is one the downsides of the Green Chemistry –based evaluation that
the toxicity of same one component is resulting in negative assessment of several of the principles.
Likewise, deeper shades of green would indicate more significant environmental, economic or social
benefits. However, the GC principles being centred on addressing sustainability on a molecular level
(Anastas 2010), the environmental and/or social benefits of products and processes are not profound.
Based solely on the intensity of green vs. red hues, one can make a very superficial evaluation. One
could conclude that using a nontoxic feedstock material as CO2 is, does substantially improve the
sustainability of the product, as compared with routes using or producing potentially toxic solvents
or derivatives. Table 2 summarizes the result of the sustainability assessment.
70
Table 2 Evaluation of DMC production routes based on green chemistry principles.
In addition, as there are no universally accepted weighing criteria in between the different principles
established, one can only make qualitative assessment in comparing the five routes. As a case in point,
it is not apparent if using catalytic routes tips the scale overall towards more positive environmental
balance when contrasted with hazardous raw materials use, such as in route 1. Similarly, one could
argue if the non-hazardous quality of by-products warrants the use of high energy impact raw materials in route 2. Finally, it is debatable if the valuable by-product in route 3 overweighs the use of
fossil-based raw material. One could assert that routes 2 and 3 appears overall the most sustainable
one; however, without being able to weigh the positive and negative impacts within the same reaction
and also against each other, this assessment cannot bring conclusive results on which one is more
favourable. It is thus concluded that the Green Chemistry principles are useful guidelines for “benign
by design” chemical process planning; however, they remain at the conceptual level. Even Anastas
pointed out, well over ten years after first publishing the 12 principles that the principles need to be
viewed as a cohesive system, in which design creates synergies amongst the principles rather than
trade-offs (Anastas 2010).
Environmental considerations have been a part of chemical process design and everyday operation
for more than a decade. However, in process planning, the end-of-pipe thinking of environmental
issues prevails. As well, the social and economic aspects of sustainability, the so-called triple bottom
line thinking is missing. Many reputable tools such as LCA are limited to environmental considerations
only. Those that take into notice all the three aspects of sustainability, such as the sustainability metrics
of the Institution of Chemical Engineers (IChemE 2002), are devised for evaluating manufacturing
facilities and are not directly suitable for use in the design phase. Conversely, sustainability considerations are the most efficient the earliest they are applied in the product’s life-cycle. The principles of
GC are useful at the design phase; however, economic and social considerations in the principles are
limited. As well, it is insufficient that the company and its processes are ‘green’; if there are negative
impacts in upstream or downstream processes, such as in the supply chain, or in distribution phase.
There is a need for metrics and tools, to translate the complex concept of sustainability into practical and measurable results at the early design phase. Our work will continue to develop a tool for
sustainability assessment that will include the full considerations of triple bottom line aspects, and
can assess chemical products at early design stages.
Acknowledgements
The authors would like to thank the Academy of Finland (projects CO2UTIL nro.11807, SUSE
nro.129173, and SusProc nro.118212) for the financial support. The authors also acknowledge the
role of MSc Alli Majala for her contribution to developing the modified GC Toolkit used in his work.
References
Anastas P (2010) Perspective on Green Chemistry: The most challenging synthetic transformation.
Tetrahedron 66 (2010) 1026–1027
Anastas P and Warner J (1998) Green Chemistry: Theory and Practice. New York: Oxford University Press.
Cavani F, Centi G, Perathoner S and Trifiro F (2009) Sustainable Industrial Process WILEY-VCH, 1-72
Chambers C (2004) Envirowise Green Chemistry Diagnostic Tool. Excel tool by WSP Environmental.
Copyright: Envirowise, UK. Archived at:
http://webarchive.nationalarchives.gov.uk/20081023145831/http://envirowise.gov.uk/uk/sectors/
chemicals-and-pharmaceuticals/green-chemistry-toolkit/about-the-toolkit.html
Delledonne D, Rivetti F, Romano U (2001) Developments in production and application of
dimethylcarbonate. Applied Catalysis A: General Vol. 221, Issues 1-2:241-251
IChemE (2002) The Sustainability Metrics. Sustainable Development Progress Metrics recommended
for use in the process industries. Institution of Chemical Engineers.
Katrib Y, Deiber G, Mirabel P, Le Calve S G C, Mellouki A and Le Bras G (2002) Atmospheric Loss
Processes of Dimethyl and Diethyl Carbonate. Journal of Atmospheric Chemistry 43, No. 3:151-174
Pacheco M A, Marshall C L (1997) Review on dimethyl carbonate manufacture and its charachteristics
as a fuel additive. Energy&Fuels 11, No.1:2-29
Rivetti F, Romano U, Delledone D (1996) Dimethyl carbonate and its production technology. In
Anastas P T, Williamson T C (eds.) Green Chemistry ACS Symposium Series 626:70-80.
72
Sustainability assessment of formic acid production:
Comparison of conventional and CO2-based processes
Linda Omodara1, Paula Saavalainen1*, Eva Pongrácz2, Esa Turpeinen1 and Riitta L. Keiski1
1
Department of Process and Environmental Engineering,
2
Thule Institute, NorTech Oulu,
1 Introduction
Sustainability assessment has gained popularity as a decision-making tool, with the idea to predict
the sustainability implications of intended actions. Sustainability assessment can be described as the
process by which decision making is directed toward sustainability. It is usually linked with derivation
of indicators which is useful in determining the current level of social, economic and environmental
factors and to state which of this sustainability related factors development is needed (Bond &
Morrison-Saunders 2011).
Carbon capture, storage and utilization (CCS and CCU) are regarded as one way of reducing the
atmospheric loading of carbon dioxide (CO2). CO2 utilization can be described as a win-win technology to both the producers/generators of CO2 and the environment. The utilization of CO2 as a raw
material can be described as both a sustainable and an inexpensive process because CO2 is natural
occurring and abundant in nature, its use has led to the reduction in greenhouse gas emissions, it is
a safe raw material, nontoxic, nonflammable. Apart from the reduction of atmospheric loading, CO2
utilization can also lead to the replacement of toxic chemicals that are harmful to human health and
environment (Raudaskoski et al. 2009).
The aim of this work was to use a green chemistry based sustainability assessment tool to compare
one conventional and two CO2 utilization routes in order to find the more sustainable way of producing formic acid. The three routes considered in this work were the Industrial route, which represented the conventional route done on a commercial scale. This method of producing formic acid is
via methyl formate hydrolysis. The experimental route and the BP patented routes represent CO2
utilization routes on laboratory scale setting and commercial setting, respectively. These methods
for producing formic acid involved the hydrogenation of CO2.
3 Results
Formic acid (HCOOH) is an alkyl carboxylic acid also known as methanoic acid. It is colorless liquid
that has a high pungent odor. It is utilized in the production of pesticides, rubber, textiles, silage additives, leather and dyes (Ullmann 2011). In this work, the production of formic acid via commercial
and laboratory scale reaction routes are considered. The methods used are an industrial process via
methyl formate hydrolysis performed in a commercial scale, and hydrogenation of CO2 both in commercial and laboratory scales. Other methods for formic acid production include oxidation of hydrocarbons, preparation of free formic acid from formates and hydrolysis of formamide (Ullmann 2011).
*Corresponding author, E-mail: paula.saavalainen@oulu.fi
Table 6 Material balance and energy consumption of the BP route (Omodara 2013).
When comparing the results in Tables 2, 5 and 6, it can be seen that while the Industrial route releases
energy (exothermic process), both CO2 routes consumes approximately the same amount of energy
(endothermic processes).
3.3 Sustainability assessments for three formic acid production processes
The sustainability assessment was done using a questionnaire based on the 12 principles of green
chemistry (Anastas and Warner 2000). Scores of -1, 1 were allocated to each question based on the
assumption that a chemical or production process either has a positive or a negative effect on the
environment, the economy and the people. The environmental, economic and social aspects of each
principle were evaluated in parallel. Table 7 shows the composite score sheet of the sustainability
assessment questionnaire. It is the sum of all principles of the Industrial, Experimental and BP routes
under the three sustainability aspects (environmental, social and economic). Table 8 illustrates the
spider charts of environmental, social, and economic sustainability assessment results.
Table 7 Score Sheet of sustainability assessment (Omodara 2013).
The results of the sustainability assessment showed that the Experimental route was the least harmful
for the environment; however, it had the highest negative composite score in terms of social sustainability, especially in terms of safer solvent use. Both CO2 utilization routes (Experimental and BP)
were more positive toward the environment than the Industrial route, which received the negative
points for the highest wastage. In terms of social sustainability, all reaction routes presented some
issues to be considered such as negative scores for the safety and degradation of chemicals. In term
of economics, all routes were economically viable, but the BP CO2 utilization route was the most
favourable in terms of atom economy. Overall, the experimental CO2 utilization route is considered
the most sustainable way to produce formic acid, once the safety issues in terms of safer chemicals
Acknowledgements
The authors like to thank the Academy of Finland (GreenCatCO2 -project) and Tekes “Carbon
Capture Storage Program” (CCSP) for financial support.
References
Anastas P and Warner J (2000) Green Chemistry: Theory and Practice. New York: Oxford University Press. P.11-34.
Bond A and Morrison-Saunders (2011) Re-evaluating Sustainability Assessment: Aligning the vision
and the practice. Environmental Impact Assessment Review. 31 (1): 1-7.
Omodara L (2013) Sustainability assessment of formic acid production: Comparison of CO2 -based
and conventional processes. Diploma thesis. University of Oulu, Department of Process and
Environmental Engineering.
Raudaskoski R, Turpeinen E, Lenkkeri R, Pongrácz E and Keiski RL (2009) Catalytic activation of CO2:
Use of secondary CO2 for the production of synthesis gas and for methanol synthesis over copperbased zirconia-containing catalysts. Catalysis Today 144 (1): 318-323
Ullmann F (2011) Encyclopedia of Industrial Chemistry. 7th edition. John Wiley and Sons. p.14-27.
78
Utilisation of industrial by-products and waste
in environmental protection “NO-WASTE”
Niina Koivikko1*, Satu Ojala1, Satu Pitkäaho1, Nicolas Bion2, Catherine Batiot-Dupeyrat2,
Ulrich Brökel3, Michael Bottlinger3, Rachid Brahmi4, Mohammed Bensitel4, Sergio Botelho5,
Joachim Zang5, Shudong Wang6, Liwei Pan6 and Riitta L. Keiski1
University of Oulu, Mass and Heat Transfer Process Laboratory, Oulu, Finland
University of Poitiers, CNRS, Institut de Chimie des Milieux et Matériaux de Poitiers,
Poitiers, France
3
University of Applied Sciences of Trier, Umwelt – Campus Birkenfeld, Germany
4
University of Chouaïb Doukkali, Department of Chemistry, El-Jadida, Morocco
5
Instituto Federal de Goias, Goiânia, Brazil
6
Dalian Institute of Chemical Physics, Dalian, China
1
2
1 Introduction
Environmental pollution is a global problem. Unsustainable production of goods, improper treatment of waste, emissions to air and water, and inadequate legislation causes growing problems to
human beings and nature. The urgent need for reducing environmental load coming from industry,
agriculture and communities demands for novel ways of thinking. NO-WASTE collaboration will
attack to this current problem by developing environmentally sound and sustainable possibilities to
utilize and valorise different wastes and emissions. The aim is to create valuable new products and
renewable energy to minimize the waste as well as emissions to air and water. As a tool to achieve
this aim, catalysis plays an important role. In addition, the sustainability of the each planned utilisation
case will be evaluated. The cases are related to hydrogen and synthesis gas production from waste,
utilization of CO2, organic gases and agricultural waste, and development of new products created
by optimized hydrothermal carbonization processes. This ambitious aim and wide operational area
demands for extensive collaboration. The exchange months during this four years program (April
2013 - March 2017) grows up to 205 months and the planned transnational network brings together
experts from different disciplines.
2 Research network
The general aim of the project is the creation of a long-term cooperation network related to the
sustainable production and waste material utilisation that will further create an established framework for the researchers to transfer the know-how between the research groups and to improve
our environment based on the results obtained during the collaboration. This exchange programme
aims to contribute to the reduction of solid, liquid and gaseous waste of several polluting industries,
agriculture and communities by transferring the waste to valuable products. This described frame
of operation allows a great number of green chemistry-related possibilities to create networks of
knowledge between the scientists of different fields (science, engineering, economy, health) in different countries (Figure 1).
*Corresponding author, E-mail: niina.koivikko@oulu.fi
Figure 1 NO-WASTE participating research groups.
Sustainable production is one of the key issues of the production technologies today. In addition
to the modifications to the processing technologies that make production more environmentally
friendly, intensive research is needed in valorisation and utilization of different by-products and wastes
produced in industry. In addition to industry, wastes are created by the communities and agriculture.
The exploitation of these wastes is important, since the amount of waste is continuously increasing
and the treatment of this waste is not adequate even today. Finding new ways to utilize industrial,
communal and agricultural waste and by-products, and transferring those to valuable products, is
the goal of NO-WASTE. We are especially aiming at to identify and develop technologies that are
potential to be used by the industry so that the reduction of the emissions and waste becomes also
economically interesting and is not just due to legislation and reputation of the company.
Figure 2 NO-WASTE frame of operation.
The more specific goals of this exchange scheme are related to the different work packages (Figure
2) that concentrate on utilisation of agricultural residues (WP1 and WP2), production of valuable
chemicals and energy from waste gases (WP3 and WP5) and utilization of mainly industrial residues
(WP4 and WP6).
WP 1 Hydrogen and synthesis gas production from waste
WP 2 Valorisation of wastes from olive and argan production
WP 3 Production of valuable chemicals from CO2 and organic gases
WP 4 R&D on the HTC technology to valorize industrial by-products and wastes
WP 5 Utilisation of methane originating from coal mining
WP 6 Research on the HTC process: Product design
80
Due to the variety of the existing industry in the participating countries this exchange programme
will concentrate on coal mines, polymer industry, food industry, but also on agriculture and municipal
waste utilisation. The sustainability of the developed products is in a central role in the planned actions and therefore assessment actions are included in the WPs when needed.
In general, waste is a mixture of several components, only in some cases waste is pure and therefore
a perfect subject for recycling and utilization. In most cases valuable or harmful components are highly
diluted in the waste. Thus specific procedures and low cost technologies are required in order to
transform waste into useful products.
Air pollution is a major threat to our health, environment and our quality of life. In spite of remarkable reductions in air emissions during the past few years in the European level, more actions are
needed to decrease air pollution further. One new approach to reduce air emissions is to transform
the treatment of the emissions to more industrially interesting actions, namely, utilization of the gaseous emissions in the production of chemicals with economic value and/or in production of energy.
The release of toxic wastewaters in the ecosystem is a remarkable source of pollution, eutrophication and perturbations of aquatic life. The presence of different pollutants in water can also cause
human health disorders. 1.1 billion people in the world have no access to clean water and 2.6 billion
people live without proper sanitation. 20% of deaths of children younger than 14 years in the world
are related to water pollution. Effective techniques for treating hazardous, toxic and highly polluted
wastewaters are a necessity of today. NO-WASTE aims to decrease also water pollution by utilizing
the waste-based products in water purification purposes.
4 Acknowledgements
This research is supported by a Marie Curie International Research Staff Exchange Scheme Fellowship
within the 7th European Community Framework Programme.
The influence of electric vehicles on CO2 emissions:
Challenges on infrastructure in cold climates
Antonio Caló,* Jean-Nicolas Louis and Eva Pongrácz
University of Oulu, Thule Institute, Centre for Northern Environmental Technology
(NorTech Oulu), P.O.Box 7300, FI-90014 University of Oulu
1 Introduction
Large scale electrification of the transportation sector is generally considered as a promising strategy
for improving efficiency and reducing greenhouse gases emissions. Within a broader decarbonization strategy (EC 2011a, EC 2011b, ETPS 2012, Förester et al. 2011), the development of the electric
vehicles (EVs) sector, including its integration within a smarter energy network, it is considered one
of the cornerstones of the future energy and transportation development strategy.
Although none of the EVs currently available is capable of replacing the services provided by conventional internal combustion engines cars, it is to be considered that electric motors are inherently
more efficient, have no tailpipe emissions, can be refuelled at home and, in standard environmental
conditions, have a better cost/mileage ratio. All this considered, the development and deployment
of EVs based system and its supporting infrastructure within the Nordic climatic and environmental
conditions requires specific evaluations and considerations. Specifically, scenarios including low temperature and peaks of demand generated by hot spots distributed over the territory can be proven
to be challenging and potentially significant limiting factors for the development of a low carbon
transportation system in the North.
This work, developed within the WintEVE project (www.winteve.fi) aimed at addressing these factors; furthermore, it intended to develop a simulation tool to be integrated with a home automation
model (Louis et al. 2013) and to be included within a larger smart energy network system (Pongrácz
et al. 2013).
Within the framework of an advanced multi-layered smart energy network system in the Northern
Finland environment (Pongrácz et al. 2013), we looked at the possibility to consider EVs as mobile
power storage devices, potentially capable to absorb energy during times of low demand and to
provide power during times of high demand.
A key target of our work was to understand the role a fleet of EVs can have on the power network of
a community. EVs have been therefore considered mobile elements of a domestic power consumption/storage system, essentially electric appliances with two peculiar characteristics: the capability of
temporarily store power and the possibility to physically interface with the power grid in locations
other than the domestic environment. More specifically we built scenarios were a selectable number
of users located across the urban areas use their EV to commute to work on a daily base.
When vehicles are parked and plugged at home, they can be simply added to the user domestic overall
energy consumption. More interesting for us was to observe the consequences for a sizable number
of EVs to be driven to few places located across the urban area which can be associated with parking
*Corresponding author, E-mail: antonio.calo@oulu.fi
82
places near large office buildings or other commercial activities; these “points of interest” represent
location where an important number of EVs are likely to be plugged/unplugged within limited time
windows and being connected for several hours. In a system based on real time energy pricing and
aiming at the flattening of the power consumption profile, redistribution of power demand across
the territory can potentially produce a significant perturbation on the local system with potentially
challenging consequences in terms of energy consumption and financial costs.
3 Results and discussion
One of the results from an earlier work (Louis 2012), was that the power consumption due to appliances for a family of 4 living in a single family house over a period of one year could be placed in
the range between 4000 and 6000 kWh (depending on a number of elements like the presence of
saunas and the behaviour of each family members). If we compare this figure with the consumption
for an EV over the same period, the overall power consumption is expected to increase from 30%
to 60% depending on a number of factors such as the amount of km and the car consumption. More
important is also the increase of power consumption during the colder months. Assuming that no
indoor parking places are made available either at the working place or at home, the amount of
energy consumption for the use of and EV in the Oulu area would increases the power consumption of another 50% in the cold months with a total increase of approximately 20% to 25% over the
yearly consumption.
Furthermore, based on the available information, a number of car manufacturers equip cars with a
recharging system capable to recharge a vehicle in a time frame of a proximately 4 to 5 hours. This is
often possible using exclusively the equipment assigned to a particular car brand. When plugged to
the common grid, the recharging time is much longer. In this condition, and with a simultaneous lack
of protected (heated) parking/recharging place, electric vehicles are likely to receive from the grid
too little power. On the other hand, fast recharging systems, capable to recharge vehicles in a time
frame of approximately 1h or less, are again specific to each car manufacturer and inflict much stress
on the batteries, increasing the indirect recharging costs in terms of aging components.
Within the considered technological and environmental conditions, our computational analysis
showed that any plan for large scale deployment of EV would have to consider significant policy
shifts and infrastructural investments. A bare replacement of conventional internal combustion
engines vehicles with electric vehicles would make the use mobile power storage, except for limited
and specific time of the year, too unrealistic: the consequences of extreme temperatures and the
limited efficiency in the car-grid interaction made the scenario substantially unfeasible, with limited
contribution to the overall power system consumption profile. Furthermore, the recharging system
considered in this work had to be assumed as schematically shown in the Figure 1. The heater, normally
believed to receive power from the battery, should be independently fed from the grid.
The analysis of the different scenarios, when observed from the power network point of view,
presented also some other issues related to the redistribution across the grid of a significant power
demand. A sizable portion of power consumption otherwise distributed across the urban areas and
different section of the power network, approximately 20% - 25%, of the yearly power consumption
per car, is concentrated, during the day time, on few specific recharging points. This causes rather
important peaks of demand especially in the winter months and, within the consider scenarios, when
power cost is the highest (if we assume a real time power purchase price).
a)
b)
Figure 1 Schematic representation for the considered option for the powering electric system heater: a)
the heater is powered by the battery that is in turn connected to the grid; b) the heater is directly and
independently powered from the grid.
As long as the fleet of electric vehicles is limited, the impact (financial, economic and environmental)
could be considered limited or even negligible. If we take in consideration, though, scenarios where
even few percentages point of the car fleet present on the territory would be electric, these factors
should be accounted for. This leave open a number of questions, whose answer reached beyond the
target of the analysis performed in this work. Nevertheless, the computational and simulation tools
for this work were developed taking these issues into consideration.
Our research team is currently working on the development of a computational analysis tool that
would allow a comprehensive study of a smart urban settlement in the Nordic environment. This
would include, among others, the integration of a component reproducing the impact of electric
vehicles and their interaction with the energy network (Pongrácz et al. 2013).
The goal of our work was to assess the potential and role of electric vehicles within a smart energy
network based system. Our investigation consisted in the development of a simulation program that
would reproduce the possible impact of a sizable fleet of electric cars in a urban northern environment and to describe the impact that such deployment could have on the power network.
Our work showed that within the Nordic climatic and environmental condition, the deployment of a
significant amount of electric vehicles will require an equally important infrastructural development.
Lack of dedicated structure (i.e. heated parking places) is indeed likely to counterbalance any improvement in GHGs emission the deployment of electric vehicles could provide. Two factors should in
particular be taken into consideration: the required high power consumption necessary for heating
the batteries and the possible concentration of power consumption is some hot spots or points of
interest (e.g. large office buildings). Both these elements require solution at the infrastructure level.
84
References
EC – European Commission (2011a) Energy Roadmap 2050, Communication from the commission
to the European Parliament, the council, the European economic and social committee and the
committee of the regions, COM(2011) 885/2, 22p.
EC – European Commission (2011b) Impact assessment accompanying the document Energy
Roadmap 2050, Commission staff working paper SEC(2011) 1565 final, 192p.
ETPS – European Technology Platform SmartGrids (2012) , SmartGrids SRA 2035 Strategic Research
Agenda, Update of the SmartGrid SRA 2007 for the needs by the year 2035, 74p.
Förester H, Healy S, Loreck C, Matthes F (2012) Decarbonization Scenarios leading to the EU
Energy Readmap 2050, Smart energy for Europe platform, Information for policy makers 1, 43p.
Louis J.-N. (2012), Smart Buildings to improve energy efficiency in the residential sector, Master's
Thesis, Oulu University, 122pp.
Louis JN, Caló A and Pongrácz E (2013) Home automation to reduce CO2 emissions associated
with energy consumption of buildings. In: Pitkäaho, Pruikkonen, Pongrácz and Keiski (eds.) (2013)
Clean air research at the University of Oulu, Proceedings of the 2nd SkyPro Conference. University of Oulu,12.11.2013, pp. 85-88.
Pongrácz E, Louis JN, Juntunen A and Caló A (2013) Decarbonization of Europe by 2050:
Motivation for Smart Energy Network development. In: Pitkäaho, Pruikkonen, Pongrácz and Keiski
(eds.) (2013) Clean air research at the University of Oulu, Proceedings of the 2nd SkyPro
Conference. University of Oulu, 12.11.2013, pp. 53-56.
Home automation to reduce CO2 emissions
associated with energy consumption of buildings
Jean-Nicolas Louis*, Antonio Caló and Eva Pongrácz
University of Oulu, Thule Institute, NorTech Oulu,
1 Introduction
With the massive deployment of smart meters across Europe allowing digital measurements, energy companies and authorities have access to a consequent database of energy consumption data
throughout a country. European Union (EU) Member States have the obligation of implementing
smart meters covering 80 % of consumers by 2020 at the latest (Office 2012). In contrast to European
Directive 2012/27/EU (Office 2012), Finnish legislation (18.1.2013/50) sets a deadline of 2014. The
deployment of smart meters also brings up the issue of data security and use of the collected information, in particular in relation to the role of energy utilities and Public Institutions (Fhom and Bayarou,
2011). Legal obligations to increase energy efficiency also provide a motivation to the deployment
of renewable energy sources, as a vector for energy production, and an increase in the energy efficiency of buildings. Home energy management can have a significant role in contributing to energy
efficiency and cutting down peak load. This can be achieved through an active collaboration of energy
consuming systems and the information network e.g. at the local level (Long Ha et al.2010). Putting
together the different factors mentioned involves the development of a smart energy network (SEN),
capable of managing the energy system through constant monitoring.
Moreover, emissions from the residential sector has been an increasingly developed topic (Hens et
al., 2001). It has been shown that (Gilbraith and Powers 2013) that electric load shifting from the
residential sector may reduce air pollution in urban areas. In this matter, developing mathematical
tools that are able to anticipate the emissions cut through the deployment of smart systems and
home automation is of major importance.
The objective of the research is to create a mathematical model of a detached house meeting the
characteristics of Northern Finland. This model has been translated into MatLab using a fuzzy logic
model for generating random houses. Nevertheless, the model is using electricity demand profile
from Nordic countries in order to create probability distribution functions that will synthetize and
contribute to the profile generated. In Fine, the research will aim at looking at the CO2 emissions
reduction from the residential sector using home automation. This research is part of a bigger umbrella project where the smart grid for a decarbonized future is studied (Pongracz et. al. 2013) by
integrating the model into a micro-grid model including electric vehicles deployment scenarios in
the North (Calo et al. 2013).
3 Results
The model aimed at drawing daily energy demand profiles coming from the appliances plus lighting
systems. Moreover, the implementation of home automation is included in the model with the aim
of increasing the effectiveness and efficiency of the household’s energy consumption. The model
used measured data in order to build up the scenario of energy demand. The modelled data were
contrasted with real-time energy consumption measurements carried out in 16 households in the
*Corresponding author, E-mail: jean-nicolas.louis@oulu.fi
86
Oulu region in 2012 (Korpela 2013). The mean daily energy demand profiles have been drawn for
the entire year in the case of the modelled dwellings and a typical four-person family house in Oulu
(Figure 1). General electricity consumption as well as the electricity price was taken every six seconds
for each phase (in the case of three-phase houses). These houses had dynamic pricing following the
spot price market. The electricity consumption recorded varied from 5 929 kWh/y up to 13 706
kWh/y for the period of January 2012 to January 2013. The mean daily energy profiles aim to recognize
a tendency in the energy production for each dwelling. A common pattern in a Finnish home sees
a peak of consumption in the evening due to the use of the sauna stove, which levels out the other
peaks occurring during the day e.g. the morning peak.
The modelled house was set for twenty-one appliances and all of the appliances were classified as
being A/B labelled. As an indicator, the sauna stove used for the modelled house was set to 6 kW.
The overall electricity consumption coming from the appliances has been found to be around 4
501 kWh/y which is correlated with the findings in the European ODYSSEE MURE project and by
the Sähkötohtori Analysis (Rouhiainen 2010). The measured data were carried out in a four-family
detached house (Oulu, Finland), which is equipped with a 10 kW sauna stove.
It is not yet clear how the offset (of approximately 400 W of average power demand) shown in
Figure 1 appeared. Our assumption is that it could be an electric under-floor heating in wet rooms,
as is common in Finnish homes. This would be on constantly during certain periods of the year and
it was not included in our model of the detached house. Earlier research has shown (Wood and
Newborough 2003, Rouhiainen 2010) that the share of electricity demand for a secondary heating
system may be considered as the highest proportion of electricity demand, reaching up to 50 % of
electricity consumption of detached houses in Finland. Nevertheless, it can be pointed out that the
trend of modelled mean power demand follows the trend of data collected in real houses, giving
confidence in the model.
Figure 1 Comparison of a dwelling modelled with real time data measured in a four-person detached
house in Oulu, Finland.
3.1 Load Shifting
In the context of flattening the daily energy demand profile, the model looked at the consequences
of consumer feedback and home automation on the mean daily electric demand. The shifting of
electricity from one particular hour to another one can be seen in Figure 2.
Figure 2 Effect of feedback strategies on demand profile in a detached house.
On one hand, the electric consumption from 12am to 6am increased by 50 %. On the other hand,
the electric demand from 7am to 12pm slightly shifted down from their original level. This longer
period of negative shift supports the decrease of energy consumption over the day. This is explained
by the feedback effect that influences the way appliances are used and offers up to 10 % reduction
of energy consumption, compared to the original demand profile.
In the context where the residential sector represents one of the biggest users of energy on the total
energy consumption, it also stresses the electric network by accumulating demand on a single hour.
These short times of high demand of electricity represent the peak load on the electric network. In
today’s electric infrastructure, the peak loads are ensured by thermal power plant running with gas
or oil. Even though it is considered to be expensive, the environmental impact is considerable and
the influence of the residential sector is of primary importance. Thus, controlling building loads may
lead to decrease pollutants emissions from centralized power production units.
References
Caló A, Louis JN, Pongrácz E, (2013) The influence of electric vehicles on CO2 emissions:
Challenges on infrastructure in cold climates. In: Pitkäaho, Pruikkonen, Pongrácz and Keiski (eds.)
(2013) Clean air research at the University of Oulu, Proceedings of the 2nd SkyPro Conference.
University of Oulu, 12.11.2013, pp. 81-84.
Fhom HS, Bayarou KM (2011) Towards a Holistic Privacy Engineering Approach for Smart
Grid Systems, in:. Presented at the 2011 IEEE 10th International Conference on Trust, Security
and Privacy in Computing and Communications (TrustCom), IEEE, pp. 234–241.
Gilbraith N, Powers SE (2013) Residential demand response reduces air pollutant emissions on
peak electricity demand days in New York City. Energy Policy 59, 459–469.
Hens H, Verbeeck G, Verdonck B (2001) Impact of energy efficiency measures on the CO2
emissions in the residential sector, a large scale analysis. Energy & Buildings 33, 275–281.
Korpela T (2013). Energy Consumption of a four persons family house in Finland.
88
Long Ha D, Ploix S, Jacomino M, Hoang Le M (2010) Home energy management problem:
towards an optimal and robust solution, in: Macia Perez, F. (Ed.), Energy Management. InTech, pp.
77–106.
Office P (2012) Directive 2012/27/EU of the European Parliament and of the Council of 25 October
2012 on energy efficiency, amending Directives 2009/125/EC and 2010/30/EU and repealing
Directives 2004/8/EC and 2006/32/EC Text with EEA relevance.
Pongrácz E, Juntunen A, Louis JN, Caló A (2013) Decarbonization of Europe by 2050: Motivation
for Smart Energy Network development. In: Pitkäaho, Pruikkonen, Pongrácz and Keiski (eds.) (2013)
Clean air research at the University of Oulu, Proceedings of the 2nd SkyPro Conference. University
of Oulu, 12.11.2013, pp. 53-56.
Rouhiainen V (2010) Decomposing Electricity Use of Finnish Households to Appliance Categories,
Presented at the Energy efficiency in domestic appliances and lighting, Proceedings of the 5th
international conference EEDAL '09, Berlin, pp. 438–455.
Wood G, Newborough M (2003) Dynamic energy-consumption indicators for domestic
appliances: environment, behaviour and design. Energy & Buildings 35, 821–841.
CO2 reduction potential of renewable
energy generation at water utilities
Lauri Mikkonen1*, Jaakko Rämö2, Riitta L. Keiski3 and Eva Pongrácz1
University of Oulu, Thule Institute, Centre of Northern Environmental Technology
(NorTech Oulu), P.O.Box 7300, FI-90014 University of Oulu
2
University of Oulu, Thule Institute, P.O.Box 7300, FI-90014 University of Oulu
3
University of Oulu, Department of Process and Environmental Engineering, Heat and Mass
1
1 Introduction
Acquisition, treatment and distribution of water and wastewater require energy. Conversely, water
can also contain kinetic or thermal energy (Siddiqi et al. 2011). There is a strong relationship between
water and energy usage, and the magnitude of energy consumption correlates strongly with water
consumption rates (Li et al. 2013). For instance, wastewater can be a valuable source of energy, but
wastewater treatment is also one of the largest energy consumers in the water sector (Frijns et al.
2011). Therefore, it is useful to consider utilizing the energy content of wastewater at water utilities
to provide for own electricity and space heating needs (Latvala 2009). Simultaneously, this will also
lead to the reduction of CO2 emissions.
The aim of this study is to estimate the energy content of wastewater sludge at Kemin Vesi Oy, and
the CO2 emission reduction potential of using anaerobic digestion for energy recovery.
3 Assessing potential methane yield and energy production
Wastewater sludge has a certain methane production potential. In this study, the value of 150 m3CH4/
tVS is used (Latvala 2009). As the potential energy production parameter for methane is expressed
as cubic meters of methane per tons of organic matter, the amount of organic matter is essential to
define by multiplying the annual amount of sludge with organic matter content of the dried sludge.
The amount of produced methane during one year was assessed by using equation (1)
Methane production = sludge production * VS - % * production potential
where
(1)
Methane production is the amount of produced methane in one year [m3CH4/a].
Sludge production is the amount of sludge produced in one year [tonnes/a].
VS - % is the organic solid matter content [%].
Production potential is the potential amount of produced methane from one
tonne of organic dry matter [m3CH4/tVS].
As equation (1) gives the output as methane production rate, the amount of energy potential is assessed by
multiplying methane production with the specific energy content of methane. Used value for specific energy
content for methane in this study is 10 kWh/m3CH4 (Rutz, 2012). In addition, in the estimation of the energy
output, it is assumed that combined heat and power (CHP) unit having a gas motor is used in order to produce
both electricity and thermal energy for the utility’s need. Electrical power conversion efficiency (ηel) is set up
to 25 % and thermal energy conversion efficiency (ηTH) 45 %, respectively. As the anaerobic digestor requires
heat in order to operate adequately, it is assumed that 5 % of the produced thermal energy is used for heating
up the process (Rutz, 2012).
*Corresponding author, E-mail: lauri.mikkonen@oulu.fi
90
CO2 reduction is assessed by setting up a zero emission factor for biogas as it is considered a renewable energy source. CO2 emissions are thus evaluated by assessing the emissions of energy production from biogas. The principle is that a proportion of energy purchased outside the utility could be
replaced with CO2 -free biogas. Different emission factors defined by Motiva 2013 are used for both
electricity and thermal energy (Hippinen et al. 2012).
3.1 Energy production potential in Kemin Vesi Oy
The amount of annually produced sludge at Peurasaari wastewater treatment plant in 2012 was
2 796 tonnes. The dry matter content of the dried sludge was measured to be 26 %, and organic
matter content (volatile solids, VS) of dried wastewater sludge was estimated to be 19.5 %. According
to data given by Kemin Vesi Oy, the energy production potential as well as electricity and thermal
energy outputs were estimated. Results are illustrated in Table 1.
Table 1 Energy production potential of anaerobic digestion at Kemin Vesi Oy (Mikkonen 2013).
According to Kemin Vesi Oy, electricity consumption at Peurasaari wastewater treatment plant in
2012 was 833 299 kWh and thermal energy consumption 775 000 kWh, respectively. Based on the
energy production potential estimate, the thermal energy output could satisfy about 45 % of heating
needs in the plant. In addition, approximately 25 % of electricity needs could be satisfied by utilizing
anaerobic digestion. In order to increase the amount of produced methane, other raw materials could
be added into the reactor, such agricultural waste and bio-waste, as these materials often have higher
methane production potential values. However, the produced energy could be used in wastewater
treatment processes and in space heating. In addition, it could be possible to sell produced electricity
to the grid (Mikkonen 2013).
3.2 The CO2 reduction potential of anaerobic digestion
Table 2 illustrates the CO2 emission reduction potential, if anaerobic digestion of wastewater sludge
was used and the produced energy was utilized on-site. In 2012, Kemin Vesi Oy was using energy
provided by Kemi power plant supplying district heat and electricity. The CO2 emissions of energy
generation at Kemi power plant are included in Table 2. Avoided use of external energy would thus
contribute to CO2 emission reduction if Kemin Vesi Oy would utilize zero CO2 emission biogas.
Table 2 CO2 saving potential in Kemin Vesi Oy based on 2012 data (Mikkonen, 2013).
As seen from Table 2, CO2 emissions could be reduced by about one third by applying anaerobic
digestion on-site. The utilization of biogas could also contribute to the climate strategy of the municipality of Kemi. Furthermore, the amount of other emissions could be also reduced, such as particle
emissions originating from Kemi power plant energy production (Mikkonen, 2013).
4 Conclusions
The aim of this study was to estimate energy potential of wastewater sludge and its CO2 emission
reduction benefits at Kemin Vesi Oy, Peurasaari wastewater treatment plant. Based on the energy
estimation and data given by Kemin Vesi Oy, the energy conversion of methane produced by anaerobic digestion in Kemi could satisfy 45 % of the heating and 25 % of electric energy needs in the
wastewater treatment plant. In addition, CO2 savings could be reduced approximately 33 % compared
to the situation in 2012, if the produced energy would be utilized on-site.
Acknowledgements
This research is performed within the Water Asset Renewable Energy Solutions (WARES) project.
The authors acknowledge the funding of Northern Periphery Programme provided for the WARES
project. The authors also thank the cooperation of Kemin Vesi Oy in this research.
References
Frijns J, Hofman J and Nederlof M (2011). The potential of (waste)water as energy carrier. Energy
Conversion and Management 65: 357-363.
Latvala M (2009) Biokaasun tuotanto suomalaisessa toimintaympäristössä. Paras käytettävissä oleva
tekniikka (BAT). [Online] Suomen ympäristökeskus, 2009. Available at:
http://www.ymparisto.fi/download.asp?contentid=106756&lan=FI.
Li WJ, LI LJ and Qiu GY (2013) General Nexus Between Water and Electricity Use and Its
Implication for Urban Agricultural Sustainability: A Case Study of Shenzhen, South China. Journal
of Integrative Agriculture 12:1341-1349.
Mikkonen L (2013). The utilization of renewable energy potential in water utilities in Northern Finland.
Diploma work. Department of Process and Environmental engineering.
Hippinen I and Suomi U (2012) Yhteenvetojen CO2 päästöjen laskentaohjeistus sekä käytettävät CO2
päästökertoimet. Motiva Oy.[Online]. Available at:
http://www.motiva.fi/files/6818/CO2-laskenta_yhteenvedot.pdf.
Rutz D (2012) Sustainable heat use of Biogas Plants. Handbook. WIP Renewable Energies.
ISBN 978-3-936338-29-4.
Siddiqi A and Anadon LD (2011) The water-energy nexus in Middle East and North Africa. Energy
Policy 39 (2011) 4529-4540, 2011.
92
Synthesis gas production by reforming of CO2-containing
process gases and biogas
Esa Turpeinen*, Mika Huuhtanen and Riitta L. Keiski
Mass and Heat Transfer Laboratory, P.O.Box 4300,
FI-90014 University of Oulu
1 Introduction
Synthesis gas (mixture of H2 and CO in various ratios) is an important intermediate building block
for the production of various valuable fuels and chemicals. The synthesis gas can then be converted
to e.g. methanol, ammonia and various liquid hydrocarbons via Fischer-Tropsch synthesis. In a purified state, the hydrogen component of synthesis gas can also be used to directly power hydrogen
fuel cells for electricity generation (Chalka and Miller 2006) and fuel cell electric vehicle propulsion
(Granovskii et al. 2006).
Synthesis gas can be produced from a wide range of solid, liquid and gaseous sources including fossil
fuels, biomass and organic wastes. While steam reforming of methane (natural gas) is the primary
route for synthesis gas, dry reforming of CO2 is an alluring alternative because from the environmental
perspective because it provides the way to consume major greenhouse gases by means of this reaction (Rostrup-Nielsen et al. 2002).
Recently, a new concept of ‘‘tri-reforming’’ has been launched and experimentally demonstrated
for the utilization of power plant flue gases for synthesis gas production, without the need for CO2
separation (Song and Pan 2004). In this concept, most of CO2 in the process gases is consumed by
the CO2 reforming reaction. Although this far the tri-reforming concept has been applied only to
power plants’ flue gases, the method can be made applicable also to flue gases or process gases of
other sectors as well.
Various sources such as CO2 containing side streams of industrial processes may be potential alternatives for synthesis gas production. Among them, coke oven gas (COG) and refinery gas (RFG)
are attractive sources for synthesis gas production. Coke oven gas is a by-product generated in the
process of producing coke from coal at high temperatures whereas refinery gas is obtained during
distillation of crude oil in the refineries. Moreover, biogas being inexpensive and renewable feedstock
offers interesting perspective for e.g. cost-effective decentralised hydrogen production.
The objective of this research was to study the viability to utilize biogas, refinery gas and coke oven gas
as a feedstock for synthesis gas production by the reforming process. Steam reforming, partial oxidation and dry reforming of those gases were cases under investigation. Another aim was to evaluate
the suitability of conventional reforming catalysts for the process. Six commercial alumina supported
catalysts were under investigation. One of them was nickel based, and the rest were noble metal
based catalysts. Nine different gas compositions were studied as a feedstock for reforming reaction.
*Corresponding author, E-mail: esa.turpeinen@oulu.fi
3 Results
As an example of the results, the evolution of outlet gas composition as a function of temperature
over Ni/Al2O3 catalyst for three different reforming cases is presented in Figures 1-3.
Figure 1 Dry reforming of coke oven gas.
Figure 2 Partial oxidation of refinery gas.
Figure 3 Steam reforming of biogas.
94
Activity tests showed that coke oven gas, refinery gas and biogas are promising feedstocks for the
production of synthesis gas by reforming. Alumina supported catalyst indicated a good overall performance (activity, selectivity and stability). Catalyst deactivation caused by carbon formation is a
significant phenomenon especially in the dry reforming.
On-site production of synthesis gas/hydrogen from secondary sources and its utilization inside the
plant can intensify the processes significantly leading cost savings. Especially, in the hydrogen or energy
intensive industrial sectors such as refining or metallurgical industry the benefit can be considerable.
The use of different secondary streams such as process and flue gases instead of primary raw materials
will decrease the requirement of primary raw materials and energy consumption.
References
Chalka SG and Miller JF (2006) Key challenges and recent progress in batteries, fuel cells, and hydrogen
storage for clean energy systems. Journal of Power Sources 159 (1) 73–80.
Granovskii M, Dincer I and Rosen MA (2006) Economic and environmental comparison of conventional, hybrid, electric and hydrogen fuel cell vehicles. Journal of Power Sources 159 (2) 1186–1193.
Rostrup-Nielsen JR, Sehested J & Norskov JK (2002) Hydrogen and synthesis gas by steam and CO2
reforming. Advances in Catalysis 47, 65-139.
Song C and Pan W (2004) Tri-reforming of methane: a novel concept for catalytic production of
industrially useful synthesis gas with desired H2 /CO ratios. Catalysis Today 98, 463–484.
96
CMOS-based capacitance measurements
for cell adhesion sensing applied
in evaluating the cytotoxicity of nanomaterials
Niina Halonen1*, Timir Datta2,3, Antti Hassinen4, Somashekar Bangalore Prakash3,5,
Peter Möller6, Pamela Abshire3, Elisabeth Smela2, Sakari Kellokumpu4 and Anita Lloyd Spetz1,6
Microelectronics and Materials Physics Laboratories, Department of Electrical Engineering,
University of Oulu, P.O. Box 4500, FI-90014 University of Oulu
2
Laboratory for MicroTechnologies, Department of Mechanical Engineering,
A. James Clark School of Engineering, University of Maryland, College Park, MD 20742, USA
3
Integrated Biomorphic Information System Laboratory, Department of Electrical & Computer
Engineering, A. James Clark School of Engineering, University of Maryland,
College Park, MD 20742, USA
4
Division of Cell Biology, Department of Biochemistry, University of Oulu,
5
Advanced Design Organization, Intel Corporation, Hillsboro, Oregon USA
6
Division of Applied Sensor Science, Department of Physics, Chemistry and Biology, Linköping
University, SE-58183 Linköping
1
1 Introduction
Nanomaterials are found in a variety of products on the market, including electronic, automotive,
cosmetic, and medical applications (such as for drug delivery and medical imaging). However, even
though the biological effects of a bulk material might be well known, at the nanoscale the very same
material may behave differently and may be harmful to health. Typically health effects are evaluated
by cytotoxicity assays and animal testing, the latter posing ethical issues. Here we introduce the use
of charge-based capacitance measurements for sensing cell adhesion to the substrate surface to
evaluate the cytotoxicity of nanoparticles (Prakash et al. 2005, Prakash & Abshire 2009). Adherent
cells normally spread out and make close contact with the substrate on which they are cultured, but
stressed cells “ball up”; this change in attachment can be sensed via a change in capacitance.
Objective of this research is to develop a device called “cell clinic” based on CMOS technology.
Adherent cells are cultivated on the surface of the IC chip designed for capacitance measurements
as indication of cell viability. Attachment of the cells (i.e. viability and proliferation) can be monitored
on-line throughout the life cycle of the cells after exposing them to potentially harmful nanomaterials.
This is fast, additional and ethical option to animal testing and the method can be applied in cancer
research as well.
3 Results
We have the capacitance sensor chips produced in a commercially available CMOS technology.
The IC chips consist of capacitance sensors arrays and readout circuitry (Figure 1 (a)). The arrays
are subdivided into four different sections for calibration, planar sensors, and two different types of
interdigitated sensors. The capacitance sensors are fully differential to increase dynamic range and
suppress noise.
*Corresponding author, E-mail: niina.halonen@ee.oulu.fi
98
3.1 Cell cultivation on the surface of the chip
Adherent epithelial kidney cells of Cercopithecus aethiops were cultured on the surface of the CMOS
sensor and the cells adhered and proliferated properly on the chip (Figure 1 (b)). Preliminary results
indicated that for interdigitated sensors the optimal sensor layout closely matches the cell size in
terms of finger width and spacing.
Figure 1 (a) Layout of the IC chip with capacitance sensor arrays and readout circuitry. (b) Microscope
image of viable adherent kidney cells of Cercopithecus aethiops on the surface of the IC chip.
3.2 Exposure to TiO2 nanowires and reference data
The technology was tested with TiO2 nanowires, which have been reported to be cytotoxic (Magrez
et al. 2009). After the confluency of the adherent kidney cells of Cercopithecus aethiops was achieved
the cells were exposed to TiO2 nanowires and the cell viability was evaluated with both the CMOS
chip and a commercial cytotoxicity kit (LIVE/DEAD® Viability/Cytotoxicity Kit, Life Technologies
Corporation). The data gained from the cytotoxicity kit will be used as reference to evaluate and
verify the cell response measured as capacitance change.
As nanomaterials are emerging the consumer market there is a clear need for additional, ethical and
fast method to evaluate the biological effects of nanomaterials in short and longer terms as well. Our
research can provide one approach to evaluate the potential harmfulness of nanomaterials.
References
Magrez A, Horváth L, Smajda R, Salicio V, Pasquier N, Forró L and Schwaller B (2009) Cellular Toxicity
of TiO2-based Nanofilaments. ACS Nano 3(8):2274-2280.
Prakash SB, Abshire P, Urdaneta M and Smela E (2005) A CMOS capacitance sensor for cell
adhesion characterization. IEEE International Symposium on Circuits and Systems (ISCAS)
Conference Proceedings Vol 1-6, 23rd-26th May 2005, Kobe Japan, 3495-3498
Prakash SB and Abshire P (2009) A Fully Differential Rail-to-Rail CMOS Capcitance Sensor With
Floating-Gate Trimming for Mismatch Compensation. IEEE Transaction on Circuits and Systems-I:
Regular Papers 56:975-986.
Ari Väliheikki1*, Tanja Kolli1, Mika Huuhtanen1, Teuvo Maunula2 and Riitta L. Keiski1
2
Dinex Ecocat Oy, Typpitie 1, FI-90650 Oulu
1
1 Introduction
Nitrogen oxide (NOx) emissions from stationary sources and mobile applications are a global concern due to their effects on nature and human health. Selective catalytic reduction with ammonia
(NH3-SCR) using vanadium-based catalysts is an efficient method to reduce NOx emissions (Wang
et al. 2013). However, vanadium-based catalysts have few disadvantages e.g. the national limitations
of vanadium usage in catalysts (Domingo 1996), a high activity in SO2 oxidation to SO3 (Busca et al.
1998) and a low resistance to alkali metals and phosphorous (Klimczak et al. 2010, Kröcher & Elsener
2008). Therefore, novel catalysts are needed to replace the vanadium-based catalysts. W-ZrCe oxide
catalysts (Li et al. 2008, Väliheikki et al. 2012) have shown promising results in NH3-SCR. The addition
of lanthanum on a Pd/CeZr three-way catalyst (TWC) is found to have a positive impact on thermal
stability, BET surface area, oxygen storage capacity (OSC) and NO conversion (Wang et al. 2010).
Due to these promising results, the effect of La addition on W-ZrCe catalysts was studied in this work.
The objective of this study is to find out the effect of tungsten and lanthanum on ZrCe oxide based
catalysts. For this purpose, W-ZrCe, La-ZrCe and W/(La-ZrCe) oxide catalysts were prepared by
a wet impregnation method. The ZrCe washcoat material was provided by Dinex Ecocat Oy. 5
wt.% of La was added on ZrCe by a wet impregnation method using lanthanum nitrate (La(NO3)3•
x H2O, Sigma Aldrich) as a precursor material. The precursor material was diluted in distilled water
and then added on the wetted support material. The solution was mixed overnight at 50°C. Then,
the samples were dried in an oven overnight at 120°C. The dried samples were calcined in a muffle
oven for one hour at 150°C, two hours at 350°C and one hour at 600°C. The preparation procedure
for the 3 wt.% W-ZrCe and W/(La-ZrCe) catalysts was the same as that for the La-ZrCe catalyst
(above). The precursor material for W was ammonium metatungstate hydrate ((NH4)6H2W12O40 •
x H2O, Sigma Aldrich).
The specific surface areas, pore volumes and pore sizes of the prepared catalysts were characterized by N2 physisorption at -195°C using a Micromeritics ASAP2020 analyzer. The specific surface
areas were determined according to the BET theory and pore volumes and pore sizes according to
the BJH theory.
The behaviour of W-ZrCe, La-ZrCe and W/(La-ZrCe) oxide catalysts were tested in activity tests.
Catalyst powder (250 mg) was packed inside a quartz tube reactor as zebra stripes with quartz wool.
The reaction gas mixture consisted of 900 ppm NO, 100 ppm NO2, 1000 ppm NH3, 10% O2, 10%
H2O and balance N2. This mixture was chosen to simulate the mean real exhaust gas compositions
to the SCR reactor. The gas flows (NO, NO2, N2O, NH3 and H2O) were analyzed by a Gasmet FT-IR
gas analyser. A paramagnetic oxygen analyzer (ABB Advance Optima) was used to analyse the volume
*Corresponding author, E-mail: ari.valiheikki@oulu.fi
100
of O2. The catalyst activity was studied at the temperature range of 150°C to 600°C by calculating
the NOx conversions using equation (1):
where cNO,in, cNO,out, cNO2,in, and cNO2,out refer to the inlet and outlet concentrations of NO and NO2.
3 Results
3.1 Characterizations
Table 1 presents the BET surface areas, BJH pore volumes and pore sizes of the studied catalysts.
After the addition of W or La on ZrCe oxide the surface area decreased by 14-19%. Similar effect
was observed in the BJH pore volumes which also decreased by 8-10%. The addition of W and La
on ZrCe increased the pore sizes by 14% and 8%, respectively, compared to the ZrCe oxide. Noteworthy was also the result that the pore volumes of the W/(La-ZrCe) catalyst were approximately
15% lower compared to the W-ZrCe and La-ZrCe oxide catalysts.
Table 1 BET surface areas, BJH pore volumes and pore sizes of the studied catalysts.
3.2 Activity experiments
The NOx conversions over the ZrCe, W-ZrCe, La-ZrCe and W/(La-ZrCe) oxides are presented in
Figure 1. The W-ZrCe oxide catalyst achieved the maximum NOx conversion of 70% at 400-460°C.
The NOx conversion decreased significantly at temperatures above 500°C. The NOx conversion
over the W/(La-ZrCe) oxide catalyst was 15-20% at the temperature range of 150-500°C. The ZrCe
and La-ZrCe oxides were not active at all in NOx reduction.
Figure 1 NOx conversions over ZrCe, W-ZrCe, La-ZrCe and W/(La-ZrCe) oxides.
Novel catalysts are needed to replace the vanadium-based SCR catalysts. The W-ZrCe oxide catalyst
was found to be a promising SCR catalyst achieving 70% NOx conversion at 400-460°C. Further
improvements are still needed to reach the level of commercial vanadium-based SCR catalysts.
However, the maximum NOx conversion of both La-ZrCe and W/(La-ZrCe) oxides were more than
50% points lower compared to W-ZrCe oxides. Based on these results, the La addition by a wet
impregnation method on ZrCe oxides cannot be recommended. However, an alternative preparation method for the La addition could improve the NOx conversions.
References
Busca G, Lietti L, Ramis G & Berti F.(1998) Chemical and mechanistic aspects of the selective catalytic
reduction of NOx by ammonia over oxide catalysts: A review. Applied Catalysis B: Environmental.
18:1-36.
Domingo JL (1996) Vanadium: A Review of the reproductive and developmental toxicity. Reproductive Toxicology. 10:175-182.
Klimczak M, Kern P, Heinzelmann T, Lucas M & Claus P. (2010) High-throughput study of the effects
of inorganic additives and poisons on NH3-SCR catalysts—Part I: V2O5 –WO3/TiO2 catalysts.
Applied Catalysis B: Environmental. 95:39-47.
Kröcher O & Elsener M (2008) Chemical deactivation of V2O5/WO3 –TiO2 SCR catalysts by additives
and impurities from fuels, lubrication oils, and urea solution I. Catalytic studies. Applied Catalysis B:
Environmental. 75:215–227.
Li Y, Cheng H, Li D, Qin Y, Xiec Y & Wang S (2008) WO3/CeO2-ZrO2, a promising catalyst for
selective catalytic reduction (SCR) of NOx with NH3 in diesel exhaust. Chemical Communications.
1470–1472.
Väliheikki A, Kolli T, Huuhtanen M, Maunula T, Kinnunen T & Keiski RL (2012) The Influence of potassium and sodium on W-ZrCe oxide NH3-SCR catalysts. East Meets West on Innovation and Entrepreneurship 2012 Conference proceedings. 327-334.
Wang C, Yang S, Chang H, Peng Y & Li J (2013) Dispersion of tungsten oxide on SCR performance
of V2O5-WO3/TiO2: Acidity, surface species and catalytic activity. Chemical Engineering Journal.
225:520–527.
Wang Q, Li G, Zhao B, Shen M & Zhou R (2010) The effect of La doping on the structure of
Ce0.2Zr 0.8O2 and the catalytic performance of its supported Pd-only three-way catalyst. Applied
Catalysis B: Environmental. 101:150–159.
102
Giorgio Lanzani1* and Gian Franco Tantardini2,3
Thule Institute, P.O.Box 7300, FI-90014 University of Oulu
Department of Chemistry, University of Milan, Via Golgi 19, IT-20133 Milan
3
Institute of Molecular Sciences and Technology, Via Golgi 19, IT-20133 Milan
1
2
1 Introduction
Aluminium is one of the most common elements in earth´s crust and therefore one of the primary
components of atmospheric dust. Due to this natural abundance, aluminium is commonly regarded
as a harmless element, yet high levels of the volatile form of aluminium may negatively affect human
health in different ways (Wu 2013, Barabasz 2002). Exempli gratia, particulate constituted by hydrated
aluminium oxide (A12O3*H2O and A12O3*3H2O), chlorinated aluminium oxide (A12O3*HCl) or carbonated aluminium oxide (A12O3*CO2) may contribute to air pollution as products of the corrosion
of air conditioners. Buchnea et al. reported that, when air conditioners are at peak operation, the
concentration of Al-based contaminant reach an unacceptably high concentration in term of health
safety (Buchnea 1976). For this reason, although aluminium is widely used in technological applications, there are still a number of factors concerning it superficial oxidation that needs to be clarified
to optimize its environmentally safe usage.
These uncertainties rise from the fact that, although the corrosion resistance of this metal is well know,
the details of its passivation mechanism are still unknown. A better understanding of this process
and the involved species would provide useful insights to the speciation of the pollutants that can
released from the surface in the atmosphere. Herein, computational ab initio methods have been
used to investigate directly the interaction with oxygen with a model aluminium surface. The major
goal of this study was to get a detailed understanding of structure and electronic properties of the
metal while the oxide-passivating layer is in forming.
3 Results
Density Functional Theory (DFT) has been employed to investigate the interaction of oxygen atoms
with the high symmetry adsorption sites of the Al (100) surface. A slab supercell approach (Fuchs &
Scheffler 1999) was chosen to model the substrate, using a (2x2) surface unit cell with a slab thickness
of four atomic layers and a vacuum region of thirteen atomic layers thick (17 Å). The O atoms were
adsorbed on one side of the slab, and thus a compensating field was introduced to take into account
the generate dipole (Neugebauer & Scheffler 1992). Only valence electrons were explicitly considered
in the simulation while the presence of core ones was accounted by using Hamann pseudopotentials
(Hamann 1989). The calculated wave functions were expanded on a plane wave basis set with an
energy cut-off of Ecut=60 Ry, using (3x3x1) special k points in the surface Brillouin zone (Monkhorst &
Pack 1976). PBE generalised gradient corrections was used for all the calculations (Perdew et al. 1996).
The temperature of the artificial Fermi smearing of the electrons was optimised to obtain optimal
convergence, with kTe=0.1 eV. FHI98md plane wave code was employed to perform the simulations
(Bockstedte et al. 1997).
*Corresponding author, E-mail: giorgio.lanzani@oulu.fi
Figure 1 Schematic diagram showing the high symmetry adsorption sites on the Al (100) surface. The
small spheres (blue) are the oxygen atoms and the larger the aluminium ones. The layers of the metal
are shown with different colours.
Different allocations of the oxygen atoms on the Al (100) surface, over its high symmetry adsorption
sites, namely the top (T), the bridge (B) and the hollow (H) sites (Figure 1) have been considered.
The energetic of subsurface oxygen possibly located under the T and the B sites have been also investigated. All calculations were performed for three different oxygen coverages: Θ =1, 0.5 and 0.25,
corresponding to (1x1), (2x1) and (2x2) oxygen monolayers, respectively. The results, in term of binding energies (BE) and equilibrium O-Al surface distances (Re) are collected in Table I. BE values were
corrected for spin polarisation energy by 1.521 eV (Stampfl & Scheffler 1996). The calculated values
for work function changes (ΔΦ) and Al-O vibrational frequencies (ω) are instead reported in Table 2.
Table 1 Calculated binding energies (BE) and equilibrium distances (Re) of oxygen on Al(100) surface.
Different adsorption sites and coverages have been considered.
Table 2 Calculated work function changes (ΔΦ) and Al-O vibrational frequencies (ω) for different the
different adsorption sites and coverages.
104
The high BE values found for Bridge and Hollow sites at the lowest (2x2) coverage are comparable
to those of 4d transition metals (Hammer & Nørskov 2000). This is in good agreement with the
experimental evidence that Al surfaces are so avid of oxygen that, under normal conditions, the O2
molecules readily dissociate when exposed to this metal, and the resultant O atoms can move fast
on the Al surface as hot atoms, or adsorb on it or penetrate into the first layers (Zhukov 1999).
The coverage degree has a strong influence on the BEs and work functions but a negligible influence
on the O-Al surface equilibrium distances. Higher coverage values correspond to lower BEs and
greater increase of the work function (Table 2). This increase could be justified there is a transfer of
electronic charge from the surface to the O atom. For the (1x1) monolayer, the relative stability of
the bridge sites and the hollow sites is reversed, and this is most likely due to the stronger repulsive
effect between charged O atoms at adjacent B sites with respect to adjacent H sites. When coverage
is low (2x2) and (2x1), the most stable adsorption site is the bridge, with a binding energy of 6.34 eV
and 6.51 eV, respectively. When the coverage increases to (1x1), the hollow site becomes the most
stable one, with a binding energy 5.68 eV. The Al (100) surface has a low atomic density (1.22 x 1015
cm-2), and the O-Al surface distances when the oxygen atom lies on the hollow site are greater (2,17
Å, 2,13 Å and 2.13 Å for Θ =1/4, Θ =1/2 and Θ =1, respectively) than those observed in alumina,
whereas for the bridge site the O-Al distances (1.82 Å, 1.78 Å and 1.73 Å for Θ =1/4, Θ =1/2 and
Θ =1, respectively) are comparable to those of the alumina. For every coverage, stable absorption
sites have been identified also between the first and second layer under the top and the bridge sites.
When the O atom is absorbed in a subsurface top site, it is located at the centre of an octahedral
cavity, about 2 Å below the surface (Table 1), and its BE decreases from 4.50 eV to 4.02 eV and to
3.68 eV when increasing coverage from (2x2) to (2x1) and to (1x1). The subsurface bridge sites are
about 1 Å below the surface, in a tetrahedral cavity (Table 1), with BEs 4.84 eV, 4.39 eV and 3.52 for
(2x2), (2x1) and (1x1) coverage.
On the basis of the obtained results, we hypothesize that the passivation process starts with the formation of localized O-Al bonds. The features of this chemisorption do not change until the coverage
reaches (2x1) that correspond to have all valences of the superficial aluminium atoms occupied. At this
point, any further increase of the coverage is occurring with the displacements of the bonds already
present and this would justify that the atomic binding energy for oxygen atom decreases when the
coverage increase beyond to the value of (2x1). A further increase of the coverage degree will results
as less favourite as the required absorption of oxygen should happen through other mechanism. This
is in agreement with that proposed by Lanthony et al (Lanthony 2012), that foresees the existence of
two distinct stages in aluminium oxidation mechanism. Having a point of discontinuity in the overall
mechanism is also justifying the fact that, along the oxidation process, oxide fragments become
unstable on the metal surface and, as a consequence are released in the atmosphere as pollutants.
References
Buchnea D and Buchnea A (1974) Air Pollution by Aluminum Compounds Resulting from Corrosion
of Air Conditioners. Environmental Science and Technology, 8(8) pp.1–4.
Barabasz W et al. (2002) Ecotoxicology of Aluminium. Polish journal of Environmental Studies, 11(3),
1–5.
Bockstedte M et al. (1997) Density-functional theory calculations for poly-atomic systems: electronic
structure, static and elastic properties and ab initio molecular dynamics. Computer Physics
Communications, 107(1-3),187–222.
Fuchs M and Scheffler M (1999) Ab initio pseudopotentials for electronic structure calculations of
poly-atomic systems using density-functional theory. Computer Physics Communications, 119(1),
67–98.
Hamann D (1989) Generalized norm-conserving pseudopotentials. Physical Review B, 40(5),
2980–2987.
Hammer B and Nørskov JK (2000) Theoretical surface science and catalysis—calculations and
concepts. In Advances in Catalysis. Advances in Catalysis. Elsevier, 71–129.
Monkhorst HJ and Pack JD (1976) Special points for Brillouin-zone integrations. Physical Review B.
13(12), 5188–5192.
Neugebauer J and Scheffler, M (1992) Adsorbate-substrate and adsorbate-adsorbate interactions of
Na and K adlayers on Al (111). Physical Review B. 46(24), 16067–16080.
Perdew JP, Burke K and Ernzerhof M (1996) Generalized Gradient Approximation Made Simple.
Physical Review Letters, 77(18), 3865–3868.
Lanthony C et al. (2012) On the early stage of aluminum oxidation: An extraction mechanism via
oxygen cooperation. The Journal of Chemical Physics, 137, 094707.
C. Lanthony, J. M. Ducéré, M. D. Corrosion, 50(1), 62–71.
Stampfl C and Scheffler M (1996) Theoretical study of O adlayers on Ru(0001). Physical Review B,
54(4), 2868–2872.
Wu S et al. (2013) Chemical constituents of fine particulate air pollution and pulmonary function
in healthy adults: The Healthy Volunteer Natural Relocation, Journal of Hazardous Materials, 260
183–191.
Zhukov V, Popova I and Yates Jr. JT (1999) Initial stages of Al(111) oxidation with oxygen–temperature
dependence of the integral reactive sticking coefficient, Surface Science, 441(2-3), 251-264.
106
Field effect sensor devices and packaging
for emissions monitoring and air quality control
Mike Andersson*, Maciej Sobocinski, Jari Juuti, Anita Lloyd Spetz, Heli Jantunen
University of Oulu, Department of Electrical Engineering,
Microelectronics and Materials Physics laboratories
FIN-90014 University of Oulu, P.O.Box 7300
1 Introduction
The increasing awareness of various adverse health effects resulting from atmospheric pollution,
ranging from simple gaseous substances such as nitrogen oxides and hydrocarbons to complex
particulate matter, has led to a rapidly growing interest in monitoring emissions from energy/industrial processes as well as the indoor and outdoor air quality in order to control/improve emissions
reduction measures and prevent human exposure to harmful levels of pollutants. Over the past two
to three decades increased efforts have therefore been made in the research and development of
various sensor technologies for monitoring of gaseous substances and lately also particles (Jaaniso et
al. 2013, Burtscher 2005). One such sensor platform, which has shown good possibilities of realizing
both direct emissions and environmental monitoring, is based on Silicon Carbide (SiC) Field Effect
Transistor (FET) devices. An example of a Metal Insulator Field Effect Transistor (MISFET) sensor
device design is shown in Fig. 1(a) for which e.g. hydrogen can adsorb dissociatively on the surface
of the catalytically active platinum (Pt) gate contact and rapidly diffuse through the gate metal, creating a layer of polarized hydrogen atoms/ hydroxide groups at the oxide side of the metal/oxide
interface. This dipole layer changes the electric field in the semiconductor, affecting the density of
mobile carriers in the near interface region, which results in a shift of the transistor's current/ voltage
characteristics, see Fig. 1(b).
The wide band gap and chemical inertness of SiC facilitates a wide range of operation temperatures
(100-600°), allowing high temperature in situ emissions monitoring of combustion processes and on
board diagnostics (OBD) of exhaust aftertreatment systems as well as improvements in the measurements of complex substances and mixtures for environmental monitoring by temperature cycled
operation, utilizing the fingerprints created when different substances interacts differently with the
sensor device at different temperatures (Lundström et al. 2007).
Figure 1 (a) Cross-sectional illustration of a gas sensitive SiC based Field Effect Transistor (b) An example
of the change in I/V-characteristics upon gas exposure (thick lines) of the device in (a).
*Corresponding author, E-mail: mikan@ifm.liu.se
108
Figure 3 displays in (a) the switch between a large and a small response to CO when either increasing the temperature or the oxygen to CO ratio and in (b) the IR signal from gaseous CO (upper panel),
corresponding to the small response, and CO adsorbed on the surface (lower panel), related to the large
response.
3.2 Materials design
Furthermore, it has been possible to conclude that the response to carbon monoxide (CO) of FET
sensors with catalytic gate materials such as Pt and iridium (Ir) correlates with the corresponding CO
oxidation characteristics on the surface of respective choice of catalyst. From Fig. 3 it can be seen
that the signal to CO exhibits a switch between a small and a large response upon increasing the
CO concentration, where the small responses corresponds to an oxygen dominated catalytic gate
contact surface and the large responses to a CO covered one (Becker et al. 2011). The CO level at
which the switch occurs is for the two different materials dependent on oxygen (O2) concentration
and temperature as well as gate material structure.
3.3 Device operation
As already seen from Fig. 3 the operation temperature has a large influence on the sensor response
towards CO and similar dependencies also exist for other substances, opening up for the possibility
of temperature cycled sensor operation to gain more of both qualitative and quantitative information
about the contents of a particular gas mixture from a single sensor device. By the application of multivariate statistics it has been possible to develop a temperature cycled scheme for the quantification
of nitrogen dioxide (NO2) in a varying gas matrix, see Fig. 4 (Bur et al. 2011).
Fig. 4 displays in (a) the sequence of temperature steps and corresponding sensor signal for the temperature cycle developed for NO2 measurements, the sensor signal in each interval 1-10 treated as a
separate parameter used in the multivariate statistical regression model to correlate the sensor signals to
NO2 concentration, as shown in (b).
Figure 5 (a) The change in I/V characteristics at 600°C over time for an encapsulated FET sensor device
as compared to a bare device (inset) (b) LTCC structure with embedded electrical leads and via holes for
packaging of gas and particle sensors for high temperature applications and corrosive atmospheres.
3.4 Device packaging
Not only the device in itself has to be adapted for different applications for optimum performance,
the application specific encapsulation and packaging has a profound effect on the long-term stability
of sensor characteristics. In Fig. 5(a) the I/V-characteristics of an encapsulated sensor device is compared to a bare sensor chip when operated at 600°C. In Fig. 5(b) an illustration of an LTCC package
under development, intended for the mounting of as well as protection of electrical leads/contacts
to gas and particle sensors, is given.
110
From the basic research on chemical interactions, transduction mechanisms, device design and
operation it has been possible to develop a sensor system, currently under commercialization, for
combustion control in district and domestic heating systems based on the SiC FET CO sensing
characteristics, markedly reducing the emissions of CO, hydrocarbons and soot (Fig. 6) from such
facilities. Furthermore, the increased sensitivity of certain device designs has led to promising results
regarding the possibilities for SiC FET based detection of volatile organic compounds (VOCs) for
indoor air quality assessments (Fig. 7).
Figure 6 In (a) the changes in sensor signal in dry air and 10% relative humidity upon exposure to 200
ppt – 1 ppm formaldehyde at a sensor operation temperature of 330°C are given. In (b) the signals from
two SiC FET sensors and the sensor-controlled flow of secondary air during one firing cycle of a 40kW
wood fuelled boiler for domestic heating are displayed with the corresponding emissions given in (c).
References
Andersson M, Pearce R, Lloyd Spetz A (2013) New generation SiC based field effect transistor gas
sensors, Sens. Actuat. B 179: 95-106.
Becker E, Andersson M, Eriksson M, Lloyd Spetz A and Skoglundh M (2011), Study of the sensing
mechanism towards carbon monoxide of platinum-based field effect sensors. IEEE Sensors Journal
11(7): 1527-1534.
Bur C, Schütze A, Andersson M, Lloyd Spetz A (2011), Hierarchical strategy for quantification of NOx
in a varying background of typical exhaust gases, in Proceedings of the IEEE International
Conference on Sensors, Limerick, Ireland, 28-31 Oct , 137-140.
Burtscher H (2005) Physical characterization of particulate emissions from diesel engines: a review
Aerosol Science 36: 896-932.
Jaaniso R, Tan O K (2013) Semiconductor gas sensors, Woodhead Publishing, Cambridge
Lundström I, Sundgren H, Winquist F, Eriksson M, Krantz-Rülcker C, Lloyd Spetz A (2007)
Twenty-five years of field effect gas sensor research in Linköping, Sens. Actuat. B 121: 247-262.
Towards low-cost activated carbons
as promising adsorbents
Minna Pirilä1*, Gerardo Cruz2, Lenka Matějová3, Kaisu Ainassaari1,
Jose Solis4, Olga Šolcová3 and Riitta L. Keiski1
2
National University of Tumbes, Department of Forestry Engineering and Environmental
Management, Environmental Analysis Laboratory, Av. Universitaria s/n Campus Universitario Universidad Nacional de Tumbes, Peru
3
Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Department of Catalysis and
Reaction Engineering, Rozvojová 135, CZ-165 02 Prague
4
National University of Engineering, Science Faculty, Functional Materials Laboratory, Av. Tupac
Amaru 210, Lima 25, Peru
1
1 Introduction
Volatile organic compounds (VOCs) and heavy metals which are mainly emitted from technological
processes and operations as a part of wastewater or emissions within pharmaceutical, mining, dye
or textile industry represent a serious environmental problem because of their harmful and toxic
effects on living organisms and human health. Adsorption in a gas phase as well as in a liquid phase
belongs among non-destructive ways how to remove these contaminants and also recover them
(Graydon et al. 2009, Rio et al. 2007, Khan & Ghoshal 2000). Moreover, the adsorbent can be reused
after regeneration.
Due to the fact that the amount of VOCs uptake on porous materials depends besides others on the
internal surface area (Chiang Y-Ch et al. 1998), activated carbons (ACs) belong in addition to zeolites
to the most used adsorbents. However, AC is traditionally manufactured from non-renewable coal
which increases the price as well as the environmental impact. Therefore, there is a need to find
alternative, inexpensive, abundant and more environmentally friendly raw materials for adsorbent
material production. A wide range of studies have been conducted to reach this aim, using different
agricultural and forest wastes as raw materials. Besides economic benefit, the use of agricultural
byproducts has environmental advantages (Bhatnagara & Sillanpää 2010).
In this study the low-cost activated carbons have been prepared from cocoa pod husk and residue
chars from pine wood gasification and dry distillation processes. Two different chemical activation
agents, potassium hydroxide (KOH) and zinc chloride (ZnCl2), two different carbonization temperatures (650 and 800 °C) and two different raw material particle-size fractions (< 0.5 mm and
0.5-1 mm) were used. After preparation the ACs were compared with each other based on their
textural properties.
Textural properties of ACs were evaluated from nitrogen and krypton physisorption measurements
at 77 K. The measurements were performed on the automated volumetric apparatus ASAP2020 Micromeritics (USA). To guarantee the precision of measured data the highly pure (99.9995%) nitrogen,
krypton and helium were used. The high precision of pressure measurements was achieved by using
the low pressure transducer with the capacity of 0.1 Torr. The equilibration time was set by several sets
of 15-fold repeated pressure measurement covering 10 s. Only after less pressure change than 0.01%
between subsequent 15-fold pressure sets was achieved the nitrogen adsorption/desorption point
*Corresponding author, E-mail: minna.pirila@oulu.fi
112
was taken. Before analysis the samples were dried at 350 °C under 1 Pa vacuum for 16 h (for analyses
including determination of micropore-size distribution) and at 105 °C under 1 Pa vacuum for 16 h (for
standard analyses including the determination of mesopore-size distribution). The specific surface
area, SBET, was evaluated from the nitrogen adsorption isotherm in the range of relative pressure p/p0
= 0.05–0.25 using the standard Brunauer–Emmett–Teller (BET) procedure (Brunauer et al. 1938).
Since the specific surface area, SBET, is not a trustworthy parameter in the case of analysis of solids
comprising micropores because the BET theory was designed for purely mesoporous or nonporous
solids, the mesopore surface area, Smeso, and the micropore volume, Vmicro, were also determined
by the t-plot method (DeBoer et al. 1966), using the Lecloux-Pirard standard isotherm (Lecloux et
al. 1979, Schneider 1995). The net pore volume, Vnet, was determined from the nitrogen adsorption
isotherm at maximum relative pressure p/p0~0.995. The pore-size distribution in mesoporous region
was evaluated from the desorption branch of the nitrogen adsorption-desorption isotherm in the
range of relative pressure 0.05< x <0.995 by the Barrett–Joyner–Halenda (BJH) method (Barret et
al., 1951) via the Roberts algorithm (Roberts et al. 1967), using the carbon standard isotherm and
the assumption of the slip-pore geometry. The pore-size distribution in the microporous region was
evaluated from the low-pressure part of the nitrogen adsorption isotherms (10 -7< x <0.05) by application of the Horvath-Kawazoe solution for the slit-pore geometry. Values of necessary parameters
were taken from the Micromeritics software (Micromeritics 2004).
Since the nature of biomass and the parameters of individual treatment steps of biomass play the key
roles in preparation of microporous activated carbons, in this study the effect of different biomasses,
chemical activators and particle-size fractions on textural properties of final activated carbons has
been investigated. Textural properties such as the specific surface area, micropore volume and micropore- and mesopore-size distributions of a set of laboratory-prepared activated carbons were
evaluated based on nitrogen and krypton physisorption measurements at 77 K in order to reveal
the best experimental conditions for the production of microporous activated carbons from Finnish
pine wood and Peruvian cocoa pod husk.
3 Results
3.1 The effect of biomass nature
Pine wood (Finland) and cocoa pod husk (Peru) were used as source biomasses for the preparation of
ACs. Contrary to the raw cocoa pod husk (CPH), the pine wood was for preparation of ACs firstly
either pyrolyzed (PW-PC) or gasified (PW-GC), and such prepared materials were subsequently
used for chemical activation. All materials were sieved before chemical activation to particle-size
fraction of 0.5-1 mm. From Table I it can be seen that while the raw CPH and pyrolyzed PW were
non-porous, possessing very low surface areas 0.46 and 0.38 m2 /g, respectively, the initial gasified
PW was already mesoporous with ~71 m2 /g.
Table I Textural properties of initial materials (particle-size fraction of 0.5-1 mm) used for preparation
of ACs.
Despite the fact that the gasified PW was porous before chemical activation, it did not contribute
positively to the evolution of microporous structure of AC via chemical activation by ZnCl2 and
carbonization at 650°C (Table 2). On the other hand, micropores were preferentially formed in the
pyrolyzed PW and both micropores as well as mesopores were formed in the CPH-based AC. A
well-established microporous-mesoporous structure of the CPH-based AC can be seen in Figure 1.
Table 2 Textural properties of ACs prepared from different raw materials, activated by ZnCl2 and
carbonized at 650 °C.
Figure 1 (a) The nitrogen adsorption-desorption isotherm at 77 K, (b) the micropore-size distribution
and (c) the mesopore-size distribution of CPH-AC.
3.2 The effect of chemical activation
Based on previous knowledge (Cruz et al., 2012) two activation procedures were examined for the
preparation of ACs, via (i) ZnCl2 and carbonization at 650°C and (ii) KOH and carbonization at 800°C.
It is evident from Table 3 that the activation by KOH/800°C was more effective in the development
of ACs porous structure than ZnCl2 /650°C and, in general, led to ACs showing higher volume of
micropores and mesopore surface area. This effect was more pronounced for the PW-PC based
AC than for the PW-GC based AC
Table 3 Textural properties of PW-based ACs, activated either by ZnCl2/650°C or KOH/800°C;
comparison with selected commercial AC.
114
3.3 The effect of particle-size fraction
Concerning the different particle-size fractions, it is obvious from Table 4 that using larger particle-size
fraction of CPH enhances the development of a microporous structure of AC activated by KOH.
Since KOH is a strong base, the structure of raw materials with particle size < 0.5 mm is destroyed
(by digestion) during the carbonization, avoiding the building of porosity.
Table 4 Textural properties of CPH-based ACs, activated by KOH and carbonized at 800°C.
With respect to the removal of VOCs in emission streams and especially heavy metals in effluents,
the development of efficient adsorbents currently represents an important topic under a keen
scientific research.
Acknowledgement
The financial supports of the Finnish Funding Agency for Technology and Innovation (Tekes)
(HYMEPRO project, reg. No. 40262/11), the Academy of Sciences of the Czech Republic and Consejo Nacional de Ciencia, Tecnologia e Innovación Tecnológica (CONCYTEC) in Peru (joint project
reg. No. 002/PE/2012) are gratefully acknowledged.
References
Barret EP, Joyner LG and Halenda PB (1951) The determination of pore volume and area distributions in porous substances. I. Computations from nitrogen isotherms, Journal of American
Chemical Society 73: 373-380.
Bhatnagara A and Sillanpää M (2010) Utilization of agro-industrial and municipal waste materials as
potential adsorbents for water treatment - A review. Chemical Engineering Journal 157: 277-296.
Brunauer S, Emmett PH and Teller E (1938) Adsorption of gases in multimolecular layers. Journal of
American Chemical Society 60: 309-319.
Chiang Y-Ch, Chiang P-Ch and Chang E-E (1998) Comprehensive approach to determining the
physical properties of granular activated carbons. Chemosphere 37 (2): 237-244.
Cruz G, Pirilä M, Huuhtanen M, Carrión L, Alvarenga E and Keiski RL (2012) Production of activated
carbon from cocoa (Theobroma cacao) pod husk. Journal of Civil and Environmental Engineering
2:109.
DeBoer JB, Lippens BC, Linsen BG, Broekhoff JCP, Heuvel AVD and Osinga ThJ (1966) The t-curve
of multimolecular N2-adsorption. Journal of Colloid and Interface Science 21: 405-414.
Graydon JW, Zhang X, Kirk DW and Jia CQ (2009) Sorption and stability of mercury on activated
carbon for emission control. Journal of Hazardous Materials 168: 978–982.
Gregg SJ and Sing KSW (1982) Adsorption. Surface Area and Porosity. Academic Press, New York,
1982.
Khan FI and Ghoshal AKr (2000) Removal of Volatile Organic Compounds from polluted air. Journal
of Loss Prevention in the Process Industries 13: 527–545.
Lecloux A and Pirard JP (1979) The importance of standard isotherms in the analysis of adsorption
isotherms for determining the porous texture of solids. Journal of Colloid and Interface Science
70: 265-281.
Micromeritics (2004) ASAP 2020 Operator's Manual, Micromeritics Instrument Corporation.
Rio S, Verwilghen C, Ramaroson J, Nzihou A and Sharrock P (2007) Heavy metal vaporization and
abatement during thermal treatment of modified wastes. Journal of Hazardous Materials 148:
521–528.
Roberts BF (1967) A procedure for estimating pore volume and area distributions from sorption
isotherms. Journal of Colloid and Interface Science 23: 266-273.
Schneider P (1995) Adsorption isotherms of microporous-mesoporous solids revisited. Applied
Catalysis A 129: 157-165.
116
The effect of sulphur and water on the activity of PdPt
based natural gas oxidation catalysts
Marja Kärkkäinen1*, Mari Honkanen2, Ville Viitanen3, Tanja Kolli1, Mika Huuhtanen1,
Kauko Kallinen4, Minnamari Vippola2, Toivo Lepistö2, Jouko Lahtinen3 and Riitta L. Keiski1
Mass and Heat Transfer Process Laboratory, , P.O.Box 4300, FI-90014 University of Oulu
2
Tampere University of Technology, Department of Materials Science,
Laboratory of Materials Characterization, P.O.Box 589, FI-33101 Tampere
3
Aalto University, School of Science, Department of Applied Physics, P.O.Box 11100, FI-00076 Aalto
4
Dinex Ecocat Oy, Catalyst research, Typpitie 1, FI-90620 Oulu
1
1 Introduction
Natural gas is one of the potential alternative fuels to meet the emission regulations set for sparkignition (SI) and compression-ignition (CI) engines. For example, the lean burn natural gas vehicles
(NGV) have lower particulate (PM) and nitric oxide (NOx) emissions than comparable diesel engines.
However, from NGV relatively high levels of unburned methane (CH4) can be emitted and, therefore
natural gas oxidation (NGO) catalysts are used to oxidize the unburned CH4. Simultaneously, other
hydrocarbons (HCs) and carbon monoxide (CO) are oxidized to less harmful compounds, i.e. CO2
and H2O (Cho et al. 2007, Gelin et al. 2003, Korakiantis et al. 2011, Mowery et al. 1999).
The lean burn natural gas engines operate at very lean conditions and PdO is known to be the most
active in methane oxidation at lean conditions. The weakness of PdO catalysts is their low resistance
against sulphur and water (Lambert et al. 1997, Mowery et al. 1999). A small amount of sulphur is
always present in exhaust gas, since natural gas contains sulphur as an impurity. Pd-Pt catalysts have
been found to have a better resistance against sulphur and water than PdO (Narui at al. 1999, Pieck
et al. 2002).
The effect of sulphur and water on Pd catalysts has been studied quite widely (Colussi et al. 2010,
Escandon et al. 2008, Gelin et al. 2003, Lampert et al. 1997, Mowery et al. 1999,) on the NGV exhaust
gas catalysts, however, the studies of sulphur and water on the PdPt catalysts are not done so much
(Corro et al. 2010, Narui et al. 1999, Pieck et al. 2002).
The aim of the study was to find the effect of sulphur-water- and water-treatment on the activity of
a natural gas oxidation (NGO) catalyst.
The used catalyst was a metallic monolith catalyst provided by Ecocat Oy. The catalyst contained
PdPt (4:1) supported on alumina based washcoat. Sulphur-water- (SO2+H2O, marked as SW) and
water-treatments (marked as W) were carried out in gas phase using a laboratory scale flow reactor.
Treatments were done at 400 °C for 5h. The used procedure has been described more detailed in
the paper (Kärkkäinen et al. 2013).
The catalysts were characterized using different methods including XRF, XPS, TEM, DRIFT and
BET-BJH. The laboratory scale light-off tests were used to define catalyst activity before and after
the SW- and W-treatments.
*Corresponding author, E-mail: marja.karkkainen@oulu.fi
3 Results
3.1 Characterization
The sulphur content in the SW-treated catalysts was determined to be 1.5 wt-% based on the XRF
results. According to the binding energies measured by XPS (Table 1) the chemical composition of
sulphur was observed to be mainly in the form of sulphates (SO42-) on the surfaces of the catalyst
(Moulder et al. 1992). The sulphate form has also been found from vehicle aged samples (e.g. Honkanen et al. 2013). DRIFT analysis give two main peaks at 1180 cm-1 and 960 cm-1. The peak at 1180 cm-1
can be indicated as aluminium sulphates and the peak at 960 cm-1 is associated to the formation of
palladium sulphates (Mowery et al. 2001).
According to the results gained by XPS, TEM and BET-BJH there are no significant structural changes in
the catalyst particle sizes or their pore sizes after the SW-treatment. The amount of sulphur detected
can be then concluded to have a deactivating effect only by chemical adsorption on the surface and
support material and, further by covering the active sites of the catalysts. Corro et al. (2010) suggest
based on their XPS studies that the presence of Pt sites lower the probability of SO2 interactions
with the surface of palladium species. Therefore the presence of Pt can lower PdOx deactivation in
methane oxidation reaction.
Table 1 Binding energies [eV] measured by XPS over fresh and SW-treated catalysts.
Based on the N2 physisoption results (Table 2) the W- and SW-treatments have only a minor diminishing influence (3-5%) on the specific surface areas (SBET ). No differences in the total pore volume
were oserved on the W-treated catalyst. Instead, the total pore volume of the SW-treated catalyst
was detected to decrease by 15%.
Table 2 Specific surface area (SBET ), total pore volume and average pore size over fresh, W- and SWtreated catalysts.
3.2 Catalytic activity
According to the laboratory scale light-off test measurements the SW-treatment was determined
to have significant diminishing affect on the catalyst activity (Fig. 1). All catalysts were oberved to
achieve 100% conversion of methane, but for example, the T50 value (50% conversion at T) for the
SW-treated sample was around 60 °C higher compared to the fresh sample (T50=350 °C). In addition, a slight decrease in the catalytic activity was observed of the W-treated catalyst.
118
Figure 1 CH4 conversion as a function of temperature over fresh, W- and SW-treated catalysts at GHSV
of 31 000 h-1; Reaction gas: 600 ppm CH4, 500 ppm CO, 10 vol-% CO2, 12 vol-% O2 and 10 vol-% H2O
in balance of N2.
Natural gas catalyst stability during its entire lifetime is essential to meet emission limits. This study
shows that water has only a minor diminishing inluence on the activity of alumina based PdPt (4:1)
catalysts. Instead, the presence of sulphur (~1.5 wt-%) with water decresed the catalyst activity
substantially. Based on the XPS results sulphur was found to be in the form of sulphate. The gained
DRITF results can indicate that sulphate is not only on the surface of the catalyst, but could form
compounds with aluminium as well as palladium.
Acknowledgements
Financial support from The Academy of Finland is gratefully acknowledged.
References
Cho HM and He BQ (2007) Spark ignition natural gas engines-a review. Energy Conversion and
Management 48:608-618.
Corro G, Cano C and Fierro JLG (2010) A study of Pt-Pd/γ-Al2O3 catalysts for methane oxidation
resistant to deactivation by sulfur poisoning. Journal of Molecular Catalysis A: Chemical 315:35-42.
Colussi S, Arosio F, Montanari T, Busca G, Groppi G and Trovarelli A (2010) Study of sulphur poisoning on Pd/Al2O3 and Pd/CeO2/Al2O3 methane combustion catalysts. Catalysis Today 155:59-65.
Escandon L, Ordonez S, Vega A and Diez FV (2008) Sulphur poisoning of palladium catalysts used
for methane combustion: Effect of the support. Journal of Hazardous Materials 153:742-750.
Gelin P, Urfels L, Primet M and Tena E (2003) Complete oxidation of methane at low temperature
over Pt and Pd catalysts for abatement of lean-burn natural gas fuelled vehicles emissions:
Influence of water and sulphur containing compounds. Catalysis Today 83:45-57.
Honkanen M, Kärkkäinen M, Viitanen V, Jiang H, Kallinen K, Huuhtanen M, Vippola M, Lahtinen J,
Keiski RL and Lepistö T (2013) Structural characteristics of natural-gas-vehicle-aged oxidation
catalyst. Topics in Catalysis 56: 576-585.
Korakiantis T, Namasivayam AM and Crookes RJ (2011) Natural-gas fuelled spark ignition (SI) and
compression-ignition (CI) engine performance and emissions. Progress in Energy and
Combustion Science 37:89-112.
Kärkkäinen M, Honkanen M, Viitanen V, Kolli T, Valtanen A, Huuhtanen M, Kallinen K, Vippola M,
Lepistö T, Lahtinen J and Keiski RL (2013) Deactivation of diesel oxidation catalysts by sulphur in
laboratory and engine-bench scale aging. Topics in Catalysis 56:672-678.
Lampert JK, Kazi MS and Farrauto RJ (1997) Palladium catalyst performance for methane emissions
abatement from lean burn natural gas vehicles. Applied Catalysis B: Environmental 14:211-223.
Moulder, JF. (1992) Handbook of X-ray Photoelectron Spectroscopy: A reference book of standard
spectra for identification and interpretation of XPS data. Perkin Elmer, Eden Prairie, 261 p.
Mowery DL and McCormic RL (2001) Deactivation of alumina supported and unsupported PdO
methane oxidation catalyst: the effect of water and sulphur poisoning. Applied Catalysis B:
Environmental 34:287-297.
Mowery DL, Graboski MS, Ohno TR and McCormick RL (1999) Deactivation of PdO-Al2O3
oxidation catalyst in lean-burn natural gas engine exhaust: aged catalyst characterization and studies
of poisoning by H2O and SO2. Applied Catalysis B: Environmental 21:157-169.
Narui K, Yata H, Furuta K, Nishida A, Kohtoku Y and Matsuzaki T (1999) Effects of addition of Pt to
PdO/Al2O3 catalyst on catalytic activity for methane combustion and TEM observations of
supported particles. Applied Catalysis A: General 179:165-173.
Pieck CL, Vera CR, Peirotti EM and Yori JC (2002) Effect of water vapor on the activity of Pt-Pd/Al2O3
catalysts for methane combustion. Applied Catalysis A: General 226:281-291.
120
Optimisation of the composition of silica-titania support
on vanadium pentoxide in formaldehyde production
Niina Koivikko1*, Anass Mouammine1,2, Satu Ojala1 and Riitta L. Keiski1
University of Oulu, Mass and Heat Transfer Process Laboratory, Oulu, Finland
University of Chouaïb Doukkali, Department of Chemistry, El-Jadida, Morocco
1
2
1 Introduction
Different catalysts have been widely tested for the oxidation of methanol to formaldehyde. Especially
different vanadium-based catalysts are under intensive investigation (Ai 1978, Behera & Parida 2012,
Deo & Wachs 1994a & 1994b, Forzatti et al. 1997, Isagualiants et al. 2005, Mann & Dosi 1973, Roozeboom et al. 1981, Zhang et al. 2008). Formaldehyde can be produced also by using mercaptans as
reactants. This is attractive, since the process will, at the same time, reduce the emissions of these
very malodorous compounds (Burgess et al. 2002, Wachs 1999). The present commercial methanol
process cannot use mercaptans as reactants since the used silver and metal oxide catalysts are deactivated due to sulfur in the feed.
Methanol and mercaptans are formed during the pulping process of wood in pulp mills. In kraft pulp
mills 70 to 80% of total VOC (Volatile Organic Compound) emissions are methanol emissions (Burgess et al. 2002, Ojala et al. 2005). Nowadays these compounds can be collected from the condensate
streams of the mill and used as an energy source (Burgess et al. 2002, Wachs 1999).
In this research work usability of pulp mill waste gas stream for formaldehyde production is investigated over vanadia and titania based catalysts. In earlier experiments, activity of three different vanadia
and titania based catalysts were tested to oxidise a methanol and methyl mercaptan mixture to
formaldehyde (Koivikko et al. 2011). With promising results obtained from the preliminary tests with
the vanadia catalyst supported on silica and titania, the next step was to proceed with the experiments to test the ratios of silica-titania in the support. This paper focuses on the activity studies of a
vanadia/silica-titania catalyst with different compositions of the support on formaldehyde production.
3 Experimental
3.1 Catalyst preparation
Different catalysts based on silica and titania as pure supports or their mixtures were prepared, by
using a sol-gel method. Precursor for titanium dioxide was titanium butoxide Ti(OBu)4 (97% SigmaAldrich) and the precursor for silicon dioxide tetraethylorthosilicate (TEOS). The final support was
obtained after drying the gel overnight, and calcining the dried gel at 500°C for 2 hours. Vanadium
pentoxide was selected as an active phase for this study based on the earlier experiments. The
precursor for V2O5 was vanadyl acetylacetonate VO(acac)2 (98% Sigma Aldrich). Deposition of the
active phase on the supports was done by the wet impregnation method. In the experiments the
0.75% vanadia loading was used with different silica-titania ratios.
3.2 Activity tests
The catalytic oxidation tests were performed in a laboratory scale reactor. For the catalytic tests 500
ppm feed concentration was used for methanol and methyl mercaptan feeds. Air flow and methyl
mercaptan flow were regulated with mass flow controllers to reach the desired methyl mercaptan
*Corresponding author, E-mail: niina.koivikko@oulu.fi
concentration. The total gas flow of 1 l min-1 was used in all experiments. Methanol was fed to the
system as a liquid through a vaporizer. Teflon tubing with heated lines was used to prevent condensation of the gas compounds inside the tubing and the measurement device. A tubular quartz reactor
was placed inside the reactor oven. In the catalytic tests the oven was heated up to 500°C with the
heating rate of 5°C min-1 starting from the room temperature. 100 mg of catalyst sample was packed
in the middle of the reactor tube with quartz wool and quartz sand. The total weight of the catalyst
sample and quartz sand in the reactor was 1 g in each experiment. Reaction product gas was analysed
with Gasmet™ CR-2000 FTIR (Fourier Transform Infrared) analyser. In the experiments the main
focus was laid on the formation of formaldehyde.
4 Results
The results from the activity tests are presented in Figure 1. Each support was tested separately and
with the addition of the active phase, vanadium pentoxide (0.75%). The loading of vanadium was low
but the results show clearly that vanadia has a huge effect on the formation of formaldehyde. Pure
supports (pure silica and pure titania) showed no significant activity for the formation of formaldehyde.
Addition of active the phase, i.e. vanadia enhances the activity of the catalyst. Based on the results it
is, however, clear that the silica-titania ratio plays an important role in the desired reaction. Addition
of titania to silica from 10 to 60 percent leads to a higher formation of formaldehyde and decreases
the optimal reaction temperature.
Figure 1 Formation of formaldehyde with different supports and catalysts.
For vanadium pentoxide supported on silica and titania (60% TiO2), the optimal temperature is
already below 400 °C, which is almost 100 °C less that with the catalyst containing 30% titania in
the support. It is good to notice that the catalyst supported on pure titania was much less active that
shows the importance of both oxides in the support. Further investigation will concentrate on final
optimization of the silica-titania ratio and on characterization of the materials to discover the reason
for improved performance.
122
References
Ai M (1978) Catalytic activity for the oxidation of methanol and the acid-base properties of metal
oxides. Journal of Catalysis 54(3): 426-435.
Behera GC and Parida K (2012) Selective gas phase oxidation of methanol to formaldehyde over
aluminium promoted vanadium phosphate. Chemical Engineering Journal 180: 270-276.
Burgess TL, Gibson AG, Furstein SJ and Wachs IE (2002) Converting waste gases from pulp
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Deo G and Wachs IE (1994b) Effect of additives on the structure and reactivity of the surface
vanadium oxide phase in V2O5/TiO2 catalysts. Journal of Catalysis 146(2): 335-345.
Forzatti P, Tronconi E, Elmi AS and Busca G (1997) Methanol oxidation over vanadia-based catalysts. Applied Catalysis, A: General 157(1-2): 387–408.
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124
Science into products and production technologies:
SkyPro Oulu Clean Air Cluster
SkyPro Oulu Clean Air Cluster is a collaboration network between academy and industry. A need
for integration of air related research know-how in Oulu was observed to be of vital importance
when co-operation with regional companies in catalysis research and especially in VOC research was
performed. SkyPro Oulu was launched by the Science into Products and Production Technologies
project during 2008-2011. The project was funded by the European Regional Development Fund
(ERDF) and jointly managed by the Department of Process and Environmental Engineering (DPEE)
at the University of Oulu and Micropolis Ii Technology Center. In the beginning of the project the
co-operation was very close with industrial partners such as Ehovoc (now Gevoc), Ecocat (now
Dinex Ecocat), Proventia Group and APL Systems. After a while Stora Enso, Ruukki, Outokumpu,
Arizona Chemicals, Genano, Fermion and Rusko Waste Centre joined the SkyPro Oulu activities.
All together seven seminars were organized, including the 1st SkyPro Conference in June 2010 which
gathered altogether 93 scientists to present their research to university and company researchers,
students and public audience.
The aim of the launching project was to establish a research center in the air related research, but
instead of building up new walls, the center was realized by developing the actively working SkyPro
Oulu network between academia and industry. The network coordinates the co-operation and
conducts research assignments arising from the industry. In addition SkyPro Oulu activities include
participating in several air related research and development projects and arranging annual seminars
on different air related topics. The next big event, after this 2nd SkyPro Conference, is participating
in organizing the Technology Days 2014 arranged in Oulu in February 2014.
The main aim of SkyPro Oulu is to develop Oulu Region into an internationally renowned centre of
excellence in air-related technologies. In order to achieve this, all researchers and industrial partners
are encouraged to join forces for efficient collaboration and also to continue their excellent work in
the field.
126
Research infrastructure in air related research at the University of Oulu
The Mass and Heat Transfer Process Laboratory (MHTPL) and SkyPro Oulu applied and received,
together with Cewic, altogether 979 k€ ERDF funding for the InDePro project (2010-2011) to develop and strengthen the infrastructure in the environmental engineering research field, especially
in materials preparation and characterization. The research infrastructure is located in the DPEE at
the University of Oulu and its activities are mainly coordinated and managed by the MHTPL.
At the moment the infrastructure in the air related research is excellent and timely including extensive and modern scientific instruments for the materials development, preparation and screening,
sample characterisation, and process screening and optimisation, as well as modelling. Besides this
the outsourced analysis services provided by the Center of Microscopy and Nanotechnology play
an important role in strengthening the research environment for e.g. materials characterization. Researchers and associated staff are competent and motivated to work towards high quality research,
publishing research results in high IF journals with peer review procedures and internationalization
in everyday activities. Thus, research infrastructures of the international research partners play also
an important role in gathering high quality research data and publishing research results. Further
development of the infrastructure at the University of Oulu will be done in cooperation with other
research communities at the University of Oulu, in research projects and with the funding from
separate infrastructure calls.
SkyPro Oulu contact information
Program Director Professor Riitta L. Keiski, riitta.keiski@oulu.fi
Coordinator Satu Pitkäaho, satu.pitkaaho@oulu.fi
skypro@oulu.fi, www.oulu.fi/skypro
128
AUTHOR INDEX
Abshire, Pamela
Ainassaari, Kaisu
Andersson, Mike
Ballivet-Tkatchenko, Danielle
Batiot-Dupeyrat, Catherine
Bensitel, Mohammed Bion, Nicolas Botelho, Sergio
Bottlinger, Michael
Brahmi, Rachid Brökel, Ulrich
Caló, Antonio
Cruz, Gerardo
Darif, Bouchra
Datta, Timir
Fabritius, Timo
El Assal, Zouhair
Epron, Florence
Haapakangas, Juho
Halonen, Niina
Hassinen, Antti
Honkanen, Mari
Huuhtanen, Mika Jantunen, Heli
Juntunen, Arttu
Juuti, Jari
Kallinen, Kauko
Keiski, Riitta L. Kellokumpu, Sakari
Kinnunen, Toni
Kočí, Kamila
Koivikko, Niina Kolli, Tanja
Kordás, Krisztián
Kukutschová, Jana
Kärkkäinen, Marja Lahtinen, Jouko
Lanzani, Giorgio
Laurén, Mika
Lepistö, Toivo
Lloyd Spetz, Anita
97
111
106
67
78
36, 40, 78
31, 78
78
78
36, 40, 78
78
53, 81, 85
111
36
99
63
40
31
63
97
97
116
15, 27, 92
99, 116
106
53
106
116
15, 19, 23, 27,
31, 36, 40, 44,
67, 72, 78, 89,
92, 99, 111, 116
120
97
19
57
78, 120
15, 99, 116
27
44
15, 116
116
102
23
116
97, 106
Louis, Jean-Nicolas Matěj, Zdeněk
Matějová, Lenka
Maunula, Teuvo
Mikkonen, Lauri
Mouammine, Anass
Murtomaa-Hautala, Mari
Möller, Peter
Nevanperä, Tuomas Niemi, Seppo Obalová, Lucie
Ojala, Satu
Omodara, Linda
Oravisjärvi, Kati Pan, Liwei
Pietikäinen, Mari Pirault-Roy, Laurence Pirilä, Minna
Pitkäaho, Satu,
Pongrácz, Eva
Prakash, Somashekar Bangalore
Rautio, Anne-Riikka
Rautio, Arja Ruokojärvi, Päivi
Ruuskanen, Juhani
Rämö, Jaakko
Saavalainen, Paula
Seelam, Prem Kumar
Smela, Elisabeth
Sobocinski, Maciej
Solis, Jose
Šolcová, Olga
Suopajärvi, Hannu
Tantardini, Gian Franco
Turpeinen, Esa
Valtanen, Anna Viitanen, Ville
Viluksela, Matti
Vippola, Minnamari
Voutilainen, Arto
Väliheikki, Ari Wang, Shudong
Zang, Joachim
53, 81, 85
57
19, 44, 57, 111
99
89
120
48
97
19, 31
23
57
19, 31, 36,
40, 78, 120
72
15, 23
78
15, 23
36, 40
111
19, 31, 40,
44, 57, 78
53, 67, 72,
81, 85, 89
97
27
23, 48
48
23
89
67, 72
27
97
106
111
111
63
102
72, 92
15
116
48
116
19
15, 99
78
78
130
132

Clean air research

Transcription

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