4. Energy and Environment - Chalmers · 2015-05-06 · Energy and Environment 56 Analysis of the...
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Transcript of 4. Energy and Environment - Chalmers · 2015-05-06 · Energy and Environment 56 Analysis of the...
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4. Energy and Environment
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Energy and Environment
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Evaluation of H2 effect on NO oxidation over a Diesel Oxidation Catalyst
Muhammad Mufti Azisa, Xavier Auvrayb, Louise Olssona and Derek Creasera
a Competence Center for Catalysis, Chemical Engineering Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
b. Department of Chemical Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
Email: [email protected]
Addition of H2 has been reported to improve NO oxidation over Pt catalyst [1].
Here, the influence of H2 on NO oxidation over Pt/Al2O3 as a model DOC catalyst
was evaluated with various DOC feed mixtures. Discrimination of surface
chemistry and exothermal effects due to addition of H2 was made based on
differences in time scales of transient responses. H2 was proposed to retard Pt
oxide formation mainly at low temperatures (ca. < 200C), whereas, at higher
temperatures Pt oxide formation was unhindered by H2. As a result, a temporal
enhancement in NO2 yield due to H2 was obtained during temperature ramp
experiments. In C3H6 containing mixtures, it was evident that the promotional role
of H2 was to weaken the inhibition effect of C3H6 by lowering the light-off
temperature for C3H6 oxidation.
Figure 1. The dynamic effects of switching in and out 750 ppm of H2 with full mixture of
DOC feed (NO/CO/C3H6 mixture)
The results from transient experiments clearly showed an increase in NO2 yield
that resulted from effects of H2 on surface chemistry and/or reactions (Figure 1).
H2 decreased the blocking effect of adsorbed C3H6 species and prevented the
reaction of C3H6 with NO2 forming NO. For a complete DOC feed mixture
(containing NO, CO, C3H6), an addition of ca. 250 ppm of H2 appeared to be
optimal, while higher H2 concentrations were disadvantageous due to NO2
consumption by H2.
Reference.
[1] J.M. Herreros, S.S. Gill, I. Lefort, A. Tsolakis, P. Millington, E. Moss, Appl. Catal. B-Environ. 147 (2014) 835-841.
Energy and Environment
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Analysis of the exoproteome to enhance the hydrolysis yield in thermophilic anaerobic digestion of cattle manure
Gautier Bailleula, Christel Kampmana, Tisse Jarlsvikb, Ulf Martinssonb, Susanna Peterssonb and Maurizio Bettigaa
aDivision of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg
bGöteborg Energi, Box 53, 401 20 Gothenburg
Email: [email protected], [email protected]
Due to global warming and the depletion of fossil fuels, there is a trend towards renewable
energy sources, such as solar power, bio-ethanol and biogas. Anaerobic digestion is an
established technology for the recovery of chemical energy from e.g. wastewater and manure
as biogas [1, 2]. Although a proven technology, research is required to increase biogas yields
and productivity.
The goal of the present research is to optimize a full-scale thermophilic anaerobic digester fed
with cattle manure. It is expected that hydrolysis of the lignocellulosic material contained in the
substrate is a limiting step [3]. This will be verified in laboratory studies, mimicking the
conditions at the full-scale digester. The exoproteome will be analyzed to characterize the
hydrolytic enzymes and to relate the enzymes to micro-organisms present in order to get an
indication how to improve hydrolysis. It is expected that this can be done through adjusting
micro and macro nutrient availability [4], addition of other substrates and selection of process
conditions like pH, temperature, feed composition or control of concentrations of inhibitors
(ammonium, volatile fatty acids). The effect of the selected parameters on the microbial
community, particularly on the excretion of hydrolytic enzymes, and the hydrolysis yield will
be established.
The expected outcome of the study is that by an improved understanding of the microbial
community, esp. the organisms responsible for hydrolysis of lignocellulosic material, the biogas
yield and biogas productivity can be increased.
References.
1. Seghezzo, L., Zeeman, G., Van Lier, J. B., Hamelers, H. V. M., Lettinga, G. (1998) A review: the anaerobic treatment of sewage in UASB and EGSB reactors. Bioresource Technology. 65 (3), 175 – 190.
2. Ward, A. J., Hobbs, P. J., Holliman, P. J., Jones, D. L. (2008) Optimisation of the anaerobic digestion of agricultural resources. Bioresource Technology. 99 (17), 7928-7940.
3. Angelidaki, I. and Ahring, B.K. (2000) Methods for increasing the biogas potential from the
recalcitrant organic matter contained in manure. Water Science and Technology. 41 (3), 189-94
4. Demirel, B. and Scherer, P. (2011) Trace element requirements of agricultural biogas digesters
during biological conversion of renewable biomass to methane. Biomass & Bioenergy. 35 (3), 992-
998
Energy and Environment
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Low Excitation Intensity Photon Up-Conversion in the Uv/Vis Region
Damir Džeboa, Karl Börjessonb, Kasper Moth-Poulsenb and Bo Albinssona
aDepartment of Chemistry and Chemical Engineering/Physical Chemistry, Chalmers University of Technology, SWE-412 96 Göteborg, Sweden
bDepartment of Chemistry and Chemical Engineering/Polymer Technology, Chalmers University of Technology, SWE-412 96 Göteborg, Sweden
Email: [email protected]
Majority of today’s solar energy harvesting technologies suffer from drawbacks
in production cost and low efficiencies due to the low and less-than-perfect ability
to absorb visible light. Additionally, many interesting photochemical reactions
require high-energy photons rather than lower-energy photons in the visible range.
One such extremely usable photocatalytic reaction is the splitting of water into
hydrogen- and oxygen gas.[1] Both of these possible applications would benefit
greatly if visible light could be effectively converted to UV or near-UV light.
One way to achieve this type of photon up-conversion is to utilize a phenomenon
called Triplet-Triplet-Annihilation (TTA).[2] In short, this phenomenon is based
on the interaction of two molecules; a sensitizer and an emitter, which merge the
energy of two low-energy photons to yield one photon of higher energy.
Our initial goal is to improve the known bi-molecularly annihilating system,
where the sensitizer is a Pd-octaethylporphyrin and the annihilator is 9,10-
diphenylanthracene[2] with the use of an oligomeric annihilator. This would
allow for an intramolecular TTA-process, as opposed to the commonly used
diffusion controlled intermolecular process, thus making the annihilation faster,
more efficient and less oxygen sensitive. This is of high interest considering that
earlier studies have shown that a great room for improvement in the photon up-
conversion through TTA lies in optimizing the annihilating part of the process.[3]
References.
[1] Khnayzer, R. S. et al Upconversion-powered photoelectrochemistry. Chem. Commun. 2012, 48, 209–211. [2] Singh-Rachford, T.N.; Castellano, F.N., Photon upconversion based on sensitized triplet-triplet annihilation. Coord. Chem. Rev. 2010, 254, 2560–2573. [3] Murakami, Y. et al Kinetics of Photon Upconversion in Ionic Liquids: Energy Transfer between Sensitizer and Emitter Molecules. J. Phys. Chem. B 2013, 117, 2487-94.
Energy and Environment
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Synthesis of Norbornadiene Photoswitches for Efficent Molecular Solar Thermal Energy Storage
A. Dreos, M. Quant, A. Lennartson, K. Börjesson, A. Roffey, A.Lundin, V. Gray, and K. Moth-Poulsen*
Chalmers University of Technology (Department of Chemistry and Chemical Engineering, Göteborg) *[email protected]
Molecular Solar Thermal Energy Storage (MOST) systems are based on molecules that absorb sunlight and convert to a high energy photoisomer [1]. The stored energy can be released (as heat) on demand by applying e.g. a catalyst (see Figures 1 and 2). The norbornadiene (NBD) – quadricyclane (QC) system is one example of compounds with potential use in MOST systems [2] (Figure 3).
Many challenges need to be addressed in order to use NBD – QC as an efficient MOST system.
The adsorption of NBD needs to be red-shifted from UV to visible light in order to achieve a better
matching with the solar spectrum and at the same time the energy barrier for back conversion (∆H‡)
needs to be sufficiently high. A strategy to red-shift the absorption was previously reported [4]. It consists
of adding aryl donor and acceptor substituents in the R1 and R2 positions (Figure 3). The previously
reported systems showed promising properties and opened the way for new compounds to be prepared.
Our current synthetic efforts are focusing on engineering the NBD – QC system by introducing a variety
of donor and acceptor substituents. In addition, substituents in the R3 position are an intriguing
modification as well. Synthesis of these new compounds is fundamental in order to create a deeper
understanding of the structure-property relation in these systems and an important step towards
realizing new technologies for solar energy storage and molecular solar thermal systems.
Fig.3 – Synthetic approaches towards substituted NBD and the NBD – QC system.
References [1] T.J. Kucharski, Y. Tian, S. Akbulatov, and R. Boulatov, Energy Environ. Sci. 4 (2011) 4449
[2] A.Lennartson, A. Roffey and K.Moth-Poulsen, Tetrahedron Lett.56 (2015)1457 [3] A. Lennartson, K. Börjesson and K. Moth-Poulsen, ACS Sust. Chem. Eng., 1 (2013) 585 [4] V. Gray, A. Lennartson, P. Ratanalert, K. Börjesson and K. Moth-Poulsen, Chem. Comm. 50 (2014) 5330
Fig.1 - A closed MOST system consisting of a solar collector, storage tank, heat extraction reactor, and
heat exchanger [3].
Fig.2 – Schematic energy diagram for a MOST system [4].
Energy and Environment
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Sources of particulate air pollutants in Nairobi, Kenya
S.M. Gaitaa, J. Bomana, M.J. Gatarib, A. Wagnerc and S. Janhälld
aDepartment of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, SE-412 96 Gothenburg, Sweden.
bInstitute of Nuclear Science and Technology, University of Nairobi, PO Box 30197, 00100 Nairobi, Kenya.
cDepartment of Applied Physics, Chalmers University of Technology, SE-41296, Göteborg, Sweden.
dSwedish National Road and Transport Research Institute, PO Box 8072, SE-402 78 Gothenburg, Sweden.
Email: [email protected]
Air pollution in urban centers is of grave concern due to its negative contribution
to human health and positive contribution to urban environmental stress. Sub-
Sahara African cities have reported increased urban population which is not at par
with the delivery of social services such as garbage collection, transportation,
energy and housing. As a result, pressure from the increasing population and lack
of adequate regulations has been linked to the said services contributing to air
pollution. Two studies conducted between 2007 and 2010, identified sources of
particulate pollutants to include traffic, industrial emissions, mineral dust and
combustion related activities (such as thermoelectric power generation, domestic
heating and open solid waste burning). In the first study, traffic and mineral dust
factors were found to contribute about 74% of the particulate matter less than 2.5
µm (Gaita et al., 2014). In the second study, airborne particulate matter was
sampled in ten size ranges and analyzed for trace elements. Statistical treatment
of the trace elements’ (K, Cu, Zn, and Pb) concentrations obtained from the size
segregated particles, highlighted the multiplicities of particulate pollutant sources.
The information from the two studies can be exploited for policy formulation and
mitigation strategies to control air pollution in Sub-Sahara African cities.
This work was funded by the Swedish International Development Cooperation
Agency (SIDA) and the International Programme in the Physical Sciences (IPPS),
Uppsala University, Sweden.
References
Energy and Environment
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Towards Intramolecular Triplet-Triplet Annihilation Photon-Upconversion
Victor Graya, Damir Dzebob, Karl Börjessona, Maria Abrahamssonb, Bo Albinssonb and Kasper Moth-Poulsena
aChemistry and Chemical engineering, Polymertechnology, Chalmers Technical University
bChemistry and Chemical engineering, Polymertechnology, Chalmers Technical University
Email: [email protected]
Photon-Upconversion through Triplet-Triplet Annihilation (TTA) is a process
that can produce one high-energy photon from two absorbed low energy photons.
Therefore Triplet-Triplet Annihilation (TTA) photon-upconversion has gained a
lot of interest lately as it might offer an efficient way of converting low energy
solar photons into higher energy photons, more suitable for solar power
production [1,2] and solar energy storage [3].
The TTA system consists of a triplet sensitizer and an emitting species, typically
metallo-porphyrins and polyaromatic molecules respectively. Two key steps are
involved in the TTA photon-upconversion process; Triplet energy transfer
between sensitizer and emitter and the triplet-triplet annihilation between two
triplet excited emitters generating one singlet-excited emitter.
To date the most efficient TTA photon-upconversion systems are bimolecular,
require liquid solutions and oxygen free environments. This is not optimal for
real-life applications, therefore we have investigated a route towards a
supramolecular system enabling the Triplet energy transfer and TTA to occur
intramolecularly. Presented here is a first step towards intramolecular TTA
photon-upconversion. A series of pyridine-terminated emitters capable of
coordinating to the triplet sensitizer have been synthesized. The effect of the inter-
chromophore distance, between sensitizer and emitter, on the triplet energy
transfer and Förster resonant energy transfer was studied. This was then correlated
to the TTA photon-upconversion capabilities of the systems. Alongside this study,
dendrimeric structures of emitter molecules were synthesized in order to examine
intramolecular TTA more specifically.
References.
1. T. Schmidt and T. Schulze, Energy Environ. Sci., 2015, 8, 103-125. 2. V. Gray, D. Dzebo, M. Abrahamsson, B. Albinssona and K. Moth-Poulsen, Phys. Chem. Chem. Phys., 2014, 16, 10345-103523.
3. K. Börjesson, D. Dzebo, B. Albinssona and K. Moth-Poulsen, J. Mater. Chem. A, 2013, 1, 8521-8524.
Energy and Environment
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Synthesis of crystal mimicking 1,3-diphenylisobenzofuran
Johansson, Fredrik† *; Albinsson, Bo‡; Mårtensson, Jerker†.
†Department of Chemistry and Chemical Engineering, Organic Chemistry, Chalmers ‡ Department of Chemistry and Chemical Engineering, Physical Chemistry, Chalmers
*Email: [email protected]
The viability of modern solar energy harvesting devices are hampered by high
production costs and limited efficiencies. The most significant of the efficiency
limiting factors in solar cells is spectrum losses. The incoming light might either
possess too little energy to participate in power production or have an excess of
energy in which the surplus is dissipated as heat. In single junction silicon based
solar cells these energy mismatches constitutes for a 50 % energy loss. One
potential strategy to diminish the energy loss due to dissipation of excess energy
is to use systems able to support singlet fission. These are multi-chromophore
systems in which an organic chromophore in its singlet excited stated shares the
excitation energy with a neighboring ground state chromophore. Resulting in a
conversion into two triplet excited chromophores. The electronic properties
needed to support this process are exotic and the systems they are commonly
found in are slip-stacked crystalline, rendering the choice of chromophore (e.g.
1,3-diphenylisobenzofuran) and chromophore-chromophore coupling limited.
Systems able to self-assemble 1,3-Diphenylisobenzofuran substrates in a slip-
stack manner is targeted within this work. The chromophore core is constructed
via gringard reaction while the linker chromophore coupling is performed by a
sp2-sp3 Suzuki-Miyaura type coupling between bromo-aryl and the terminal
alkene moiety. The synthesis is designed to accommodate variations of the linker
and anchor group, as well as being mild enough to ensure stability of the otherwise
sensitive 1,3-diphenylisobenzofuran functionality.
Energy and Environment
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An engineered Saccharomyces cerevisiae for cost-effective lignocellulosic bioethanol production: process performance and
physiological insights
Antonio D. Morenoa, Elia Tomás-Pejóab, Cecilia Geijera and Lisbeth Olssona
aDepartment of Biology and Biological Engineering, Industrial Biotechnology, Chalmers University of Technology, Këmivagen 10, Gothenburg, Sweden.
bIMDEA Energía, Biotechnological Processes for Energy Production Unit, Móstoles, Spain.
Email: [email protected]
The success in the commercialization of lignocellulosic bioethanol relies on the
development of microorganisms with efficient hexose and pentose fermentation
and tolerance towards inhibitory by-products (acetic acid, furan aldehydes and
phenolics) generated during biomass processing. Traditionally, the yeast
Saccharomyces cerevisiae is the preferred microorganism for industrial ethanol
production. Many years of research and development have been conducted to
develop S. cerevisiae strains suitable for fermenting lignocellulosic-based
streams. S. cerevisiae is robust and ferment glucose efficiently, but it has been
proved to be difficult to genetically modify for efficient xylose fermentation.
In this work, a xylose-fermenting S. cerevisiae strain was subjected to
evolutionary engineering, boosting its robustness and xylose fermentation
capacity. The evolved strain was able to ferment a non-diluted enzymatic
hydrolysate (representing 23% (w/w) dry matter of steam-exploded wheat straw),
reaching ethanol titers higher than 5% (w/w) after 48 h. Within the first 24 h,
glucose and xylose were co-consumed with rates of 3.1 and 0.7 g/L h,
respectively, and converted to ethanol with yields corresponding to 93% of the
theoretical. In addition, once glucose was depleted, xylose was consumed with a
similar rate until reducing 70% of its initial concentration (36 h after inoculation).
Besides evaluating the fermentation parameters, the differences in gene
expression levels and enzymatic activities of xylose-assimilating pathway will be
further investigated. These analyses will be the foundation for understanding the
improved phenotype and the physiological mechanisms for efficient xylose
fermentation, after which potential targets for subsequent metabolic engineering
may be identified.
Energy and Environment
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Environmental Molecular Beam Studies of Gas-Surface Interactions
Sofia M. Johansson1,*, Xiangrui Kong1,2, Panos Papagiannakopoulos1,3, Erik S. Thomson1, and Jan B. C. Pettersson1
1Dept. of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, Sweden.
2Laboratory of Radiochemistry and Environmental Chemistry, Paul Scherrer Institute, Switzerland.
3Dept. of Chemistry, University of Crete, Greece.
The environmental molecular beam (EMB) method is a technique that makes
it possible to study molecular interactions with different surfaces under conditions
relevant to the atmosphere. The details in gas-surface processes are vital for
determining the properties and action of particles in the atmosphere, thus this
technique can be used to improve the knowledge in this field.
In the EMB method a directed low density flow of molecules passes through
a vacuum chamber into a smaller chamber with an elevated pressure. The beam
molecules hit a surface inside the chamber and the out going flux can be detected
with mass spectrometry. Compounds such as water and organics can be
introduced into the chamber to increase the pressure inside and to coat the surface
with adlayers; interactions between beam molecules and these different types of
surfaces can thus be studied.
During the last year the EMB setup has been improved to increase the
pressure in the high-pressure zone up to 10 Pa. Here we describe the recent
technical development, and results from initial experiments with water ice and
organic surfaces. The results indicate that the changes made to the method enable
studies of the kinetics and dynamics of gas-surface interactions at pressures
relevant to the lower atmosphere.
References:
X.R. Kong, E.S. Thomson, P. Papagiannakopoulos, S.M Johansson, and J.B.C.
Pettersson, Water Accommodation on Ice and Organic Surfaces: Insights from
Environmental Molecular Beam Experiments, J. Phys. Chem. B 118 (2014)
13378-13386.
Energy and Environment
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Alternative biomasses for biofuels
Joakim Olssona, Viktor Anderssonb, Thore Berntssonb, Eva Albersa
a Dept. Biology and Biological Engineering-Industrial Biotechnology, Chalmers University of Technology, 412 96 Göteborg, Sweden
b Dept. Energy and Environment-Industrial Energy Systems and Technologies, Chalmers University of Technology, 412 96 Göteborg, Sweden
Email: [email protected]
In Sweden, biofuels account for 4% of the total petroleum consumption (1). About
two thirds of the consumed biofuels are made in Sweden using rapeseed, wheat,
barley and left-over wine as raw materials (2), while the rest is imported (1). All
of these resources are from traditional agriculture and requires land, fertilizers,
and freshwater. While these types of biomasses will surely play a role in a future
sustainable transportation sector, other biomass alternatives are also needed.
Micro- and macroalgae require no arable land and can grow on waste resources,
such as waste water, or need no other fertilizer than the sea provides naturally.
However, to realise algae biofuels targeted technological research efforts
regarding cultivation and refining processes are required (3).
In this cooperation project between the divisions of Industrial Biotechnology and
Industrial Energy Systems and Technologies, we aim to investigate the biofuel
potential of micro- and macroalgae in Sweden. Modelling tools will be utilized to
determine what biofuels that potentially could be made from different Swedish
biomasses. All biofuels will not evaluated but bioethanol, hydrothermal
liquefaction, gasification, lipid extraction and others will be considered for
modelling depending on the content of the biomasses. In addition, the area
efficiency and energy demands during production of the biomasses will be
investigated. For such models, detailed knowledge regarding the biomasses’
content, cultivation techniques, performance, and refining processes are needed.
For microalgae, a lot of literature data exists, but with macroalgae there are gaps
in the knowledge regarding their biochemical composition, especially for the
West coast of Sweden. These gaps will, in part, be filled within this project, where
25 macroalgae and filamentous algae species have been collected. Out of these,
candidate species with good chemical content for biofuel production will be
chosen and the project will focus on how they can be cultivated and refined.
References.
1. U.S. Energy Information Administration
http://www.eia.gov/cfapps/ipdbproject/IEDIndex3.cfm?tid=5&pid=5&aid=2 [cited 2015 23-3].
2. Hamelinck C, de Lovinfosse I, Koper M, Beestermoeller C, Nabe C, Kimmel M. renewable
energy progress and biofuels sustainability.
http://decarboni.se/sites/default/files/publications/115618/renewable-energy-progress-biofuels-sustainability.pdf: Ecofys, 2012.
3. Swedish Research and Innovation Strategy for a Bio-based Economy. R3:2012.
Energy and Environment
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Molecular Solar Thermal Systems: Concepts, Solar Spectrum Matching and Catalysts
Anna Roffey, Karl Börjesson, Anders Lennartson, Victor Gray, Maria Quant, Ambra Dreos, Angelic Lundin and Kasper Moth-Poulsen
Chalmers University of Technology
Email: [email protected]
Solar energy conversion and solar energy storage are key challenges for a future
society with limited access to fossil fuels. Certain compounds that undergo light-
induced isomerisation to a metastable isomer can be used for storage of solar
energy, so-called molecular solar thermal (MOST) systems. Exposing the
compound to sunlight will generate a high-energy photoisomer that can be stored.
When energy is needed, the photoisomer can be catalytically converted back to
the parent compound, releasing the excess energy as heat. Here we present an
overview of our research efforts on harnessing solar energy in the form of
chemical bonds and then catalytically releasing that energy in the form of heat.
Our work is both focused on development of new materials for improved
matching to the solar spectrum,1-2 the development of new catalysts for heat
release and implementation of MOST systems in functional devices.3-4 For the
first time, we demonstrate the potential for both energy storage and energy release
in a continuous flow device geometry.
Figure 1. A potential MOST device geometry, showing solar collector and
heat exchanger.
References.
1. Gray, et al., Chem. Commun., 2014, 50, 5330. 2. Börjesson, et al., ACS Sustainable Chem. Eng., 2013, 1, 585. 3. Moth-Poulsen, et al., Energ. Environ. Sci., 2012, 5, 8534. 4. Börjesson, et al., J. Mater. Chem. A, 2013, 1, 8521.
Energy and Environment
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Neat C60:C70 buckminsterfullerene mixtures enhance polymer solar cell performance
Amaia Diaz de Zerio Mendaza,1 Jonas Bergqvist,2 Olof Bäcke,3 Camilla Lindqvist,1 Renee Kroon,1,4 Feng Gao,2 Mats R. Andersson,1,4 Eva Olsson,3 Olle Inganäs2 and
Christian Müller*1
1 Department of Chemical and Biological Engineering/Polymer Technology,
Chalmers University of Technology, 41296 Göteborg, Sweden
2 Biomolecular and Organic Electronics, IFM, Linköping University, 58183
Linköping, Sweden
3 Department of Applied Physics, Chalmers University of Technology, 41296
Göteborg, Sweden
4 Ian Wark Research Institute, University of South Australia, Mawson Lakes,
South Australia 5095, Australia
We demonstrate that bulk-heterojunction blends based on neat, unsubstituted
buckminsterfullerenes (C60, C70) and a thiophene-quinoxaline copolymer (TQ1)
can be readily processed from solution. Atomic force and transmission electron
microscopy as well as photoluminescence spectroscopy reveal that thin films with
a fine-grained nanostructure can be spin-coated and display a good photovoltaic
performance. Replacement of substituted fullerenes with C60 or C70 only results
in a small drop in open-circuit voltage from 0.9 V to about 0.8 V. Thus, a power
conversion efficiency of up to 2.9 % can be maintained if C70 is used as the
acceptor material. Further improvement in photovoltaic performance to 3.6 % is
achieved, accompanied by a high internal quantum efficiency of 75 %, if a 1:1
C60:C70 mixture is used as the acceptor material, due to its improved solubility in
ortho-dichlorobenzene.
Fugure 1: Solutions of ~2 g L-1 C60, C70 and a 1:1 C60:C70 mixture in oDCB; insets: chemical structures
of the fullerenes.
Energy and Environment
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Hydrometallurgical processing of fluorescent lamp waste for the recovery of critical metals
Cristian Tunsu, Christian Ekberg, Teodora Retegan
Nuclear Chemistry and Industrial Materials Recycling, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 412 96 Gothenburg,
Sweden
Email: [email protected]
Recovery and reuse of materials is important for a circular economy. In the last
years, recovery of critical metals from end-of-life products has received increased
attention. Various streams e.g. permanent magnets, nickel metal hydride batteries
and fluorescent lamps are considered as targets for the recovery of rare earth
elements (REEs). The last category can be a source of up to six different REEs:
europium and yttrium (primarily), and lanthanum, cerium, terbium, gadolinium
(secondary). The presence of mercury in fluorescent lamps requires a
decontamination step prior to REEs recovery.
Hydrometallurgical methods have been studied both for the decontamination of
fluorescent lamp waste fractions and the subsequent recovery of the REEs. A
selective leaching process, followed by separation of metals using solvent
extraction, was developed. Mercury is leached in a first stage using iodine in
potassium iodide solutions and can be further processed using either ion
exchange, reduction or solvent extraction. Impurity metals such as calcium and
barium are selectively leached from the REEs with nitric acid solution by making
use of their fast dissolution kinetics. Further leaching, carried out with more
concentrated acidic solutions, for longer time, leads to the dissolution of the REE-
containing phosphors.
Separation of the REE ions in solution is carried out via solvent extraction, using
a commercial mix of trialkyl phosphine oxides (Cyanex 923). Stripping using
hydrochloric acid solutions led to the recovery of the REEs as chlorides in acidic
solution. Testing of the process in mixer-settlers showed promising results,
leading to a final product consisting of yttrium-rich REEs concentrate. From here,
the REEs can be further purified e.g. using more selective extractants,
chromatographic techniques, precipitation using oxalic acid/calcination etc.
Energy and Environment
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Phosphorous Recovery from Waste Streams
Rikard Ylmén, Anna Gustafsson and Jinfeng Tang
Energy and Material, Chemistry and Chemical Engineering, Chalmers University of Technology
Email: [email protected],
Phosphorous is an essential element for all living beings with no possible substitute. It is a
chemical element and is therefore not finite, however the workable findings of phosphorous
minerals are. Through the history, phosphorous has seemed to be inexhaustible and has been
used as it was. Due to the rapid population growth and depleting phosphorous reserves, there is
both an environmental as well as an economical reason to recover and reuse phosphorous. To
estimate for how long the reserves of usable phosphorous will last is very difficult. The
difficulty lies in the economy of extracting the ore and the shifting demands with respect to the
price. With a more expensive ore, the incentive for recycling will increase.
Today there is legislation determining how much companies and municipal waste water plants
are allowed to release to natural waters. The main purpose of present legislation is to prevent
eutrophication. The current dominating method to remove phosphate from waste water is
therefore to add cheap metal ions, such as Ca2+, Al3+ or Fe3+ to precipitate the phosphate. The
precipitate forms a sludge that has found little practical use. The current projects at Industrial
Materials Recycling aims at finding alternative methods to remove phosphorous from waste
water that makes it easier to reuse the phosphorous.
One of the projects is a co-project between AkzoNobel Pulp and Performance Chemicals and
Chalmers University of Technology. It is a part of Mistra Closing the Loop program.
Currently there are also two diploma work within phosphorous recovery. One is performed
together with Volvo Trucks AB and studies the possibility to recover phosphate from zinc
phosphate conversion coating process that is used to increase corrosion resistance. In the other
diploma work phosphorous is recovered by solvent extraction from waste incineration ash
leachate.
Figure. A crystal cluster of (NH4)2[Mg(H2O)6]3(HPO3)4 precipitated from an ammonium
phosphite solution.
References.
D. Cordell, A. Rosemarin, J.J. Schröder, A.L. Smit, Towards global phosphorus security: A systems framework for phosphorus recovery and reuse options, Chemosphere, 84 (6), 2011, pages 747-758.
Energy and Environment
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How to investigate the extreme conditions for metallic bipolar plates in HT-PEM fuel cells
Gert Göranssona, Patrik Alnegrena, Jan Groliga and Jan-Erik Svenssona
a The Fuel Cell Group, Chalmers University of Technology, 41296 Gothenburg, Sweden
Email: [email protected]
High temperature polymer electrolyte membrane fuel cells (HT-PEMFC) are
addressing the temperature region of 100-200 oC [1]. The major components of a
PEMFC are the membrane, the anode and cathode, the gas diffusion layer and the
bipolar plate (BPP) which is main target in this study. The BPP conducts the
current generated by the cell and also serves as a gas distributor to the anode on
one side and the cathode on the other side. The bipolar plates in a HT-PEMFC
stack are currently made of graphite due to its ability to conduct current well and
its high stability in the very corrosive environment in a HT-PEMFC. The
downside of graphite is its brittleness and the BPP has to be made relatively thick
to allow sufficient mechanical stability and low gas permeability. This increases
the size and the weight of the stack substantially compared to if metal BPPs were
to be used.
Fuel cell tests with BPP of 316 steel have been performed and complemented with
a novel type of oven test that simulates the FC environment. Additionally classical
electrochemical corrosion studies at HT were performed (Figure 1). By comparing
the results from the more transparent tests with the results from the fuel cell test
it is believed that a more comprehensive picture of the impact on the BPPs at the
different situations occurring in a fuel cell can be gained. When a proper tool for
testing BPP in HT-PEMFC has been set up, new materials can be developed and
tested in a more systematic and time efficient way.
Figure 1. HT-PEMFC, oven test setup and classical EC corrosion study
of BPP material.
References.
[1] Amrit Chandan, Mariska Hattenberger, Ahmad El-kharouf, Shangfeng Du, Aman Dhir, Valerie Self
Bruno G. Pollet, Andrew Ingram, Waldemar Bujalski, Journal of Power Sources, 231 (2013) 264-278.
-0.5 0 0.5 1.0 1.510-7
10-6
10-5
10-4
10-3
10-2
10-1
E vs. RHE (V)
i (A
)
316gr2taf_8_44 dlptsg9.txt316dgrT155tafpit_last_93.txt
155 oC
22 oC
Energy and Environment
70
Biomimetic oxidative NHC-catalysis via multistep electron transfer permitting the use of air as the terminal oxidant
Linda Taa, Anton Axelssona and Henrik Sundéna
aDepartment of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96
Email: [email protected]
Oxidation reactions are important transformations in organic chemistry, however,
many oxidation reactions often uses hazardous chemicals and generates large
amounts of waste, which do not fulfil the requirements of green chemistry.1 A
greener alternative would be to use molecular oxygen in the form of air as the
terminal oxidant. However, aerobic oxidations are often difficult to achieve as the
energy barrier of transferring electron from the substrate to the oxidant is too
high.2 Nature has solved this problem with the use of enzymes. With inspiration
from nature, we envisioned mimicking the electron transfer process via electron
transfer mediators (ETMs) in combination with oxidative NHC-catalysis. With
this approach we have managed to transform α,β-unsaturated aldehydes to esters
using oxygen from the air as the terminal oxidant (Figure 1). The reaction is
performed with low catalyst and ETMs loadings, can be run at room temperature,
and generally finished after 4 hours in which the esters can be isolated in good to
excellent yields. Aided by ETMs, air can be used as the terminal oxidant, avoiding
the use of a stoichiometric oxidant, thereby offering an atom economical reaction
since water is generated as the sole by-product. The reaction is safe and efficient
demonstrating its attractiveness both from an economical and environmental point
of view.
Figure 1. Biomimetic oxidative NHC-catalysis with ETMs and oxygen as
terminal oxidant.
References.
1. Modern Oxidation Methods (Ed: J. E. Bäckvall), VCH-Wiley, Weinheim, 2004
2. Piera, J., Bäckvall, J.E. Angew. Chem. Int. Ed., 2008, 47, 3506
