| 1. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 2. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 3. |
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| 4. |
- Bhattar, Srikar, et al.
(författare)
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110th Anniversary : Dry Reforming of Methane over Ni- and Sr-Substituted Lanthanum Zirconate Pyrochlore Catalysts: Effect of Ni Loading
- 2019
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Ingår i: Industrial & Engineering Chemistry Research. - : AMER CHEMICAL SOC. - 0888-5885 .- 1520-5045. ; 58:42, s. 19386-19396
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Tidskriftsartikel (refereegranskat)abstract
- Pyrochlores are thermally stable materials that can be doped with a metal to produce active catalyst for dry reforming of methane (DRM). La1.95Sr0.05Zr1.904Ni0.096O7-d (LSNZ1) and La1.95Sr0.05Zr1.44Ni0.56O7-d (LSNZ6), with 1 and 6 wt % Ni loading at Zr site, respectively, were investigated for DRM. XRD of fresh catalysts confirmed the formation of pyrochlore structure. Also, the presence of the La2NiZrO6 perovskite phase and NiO phase indicated low substitution of Ni in the pyrochlore structure. TPSR and DRM long runs carried out at 900 degrees C and 45 h time on stream confirmed that LSNZ6 was more active than LSNZ1, which is attributed to higher Ni content and dispersion of Ni in LSNZ6. In both the catalysts, the pyrochlore structure was stable during the reaction, but the perovskite phase was reduced to respective metal oxides. No carbon deposition was observed on both the catalysts during 900 degrees C DRM runs for 45 h. Also, no sintering of catalyst was observed from XRD and TPR.
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| 5. |
- Kumar, N., et al.
(författare)
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Bi-reforming of methane on Ni-based pyrochlore catalyst
- 2016
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Ingår i: Applied Catalysis A. - : Elsevier. - 0926-860X .- 1873-3875. ; 517, s. 211-216
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Tidskriftsartikel (refereegranskat)abstract
- A Ni-based pyrochlore catalyst was synthesized using the modified Pechini method. In this method, 1 wt% Ni was doped into the La2Zr2O7 pyrochlore structure. The catalyst was characterized by H2-TPR, TPO, XRD, and EXAFS, and tested for its methane reforming activity under bi-reforming reaction conditions; i.e.; in the presence of CO2 and steam: 3CH4+CO2+2H2O⇌4CO+8H2 Repeated TPR/TPO cycles showed that the two consecutive TPR spectra do not change, showing that the catalyst is stable at high temperatures, and that the nickel oxidation/reduction process is reversible. The catalyst showed constant activity with time at all temperatures in the range of 700-950 °C over a cumulative period of 170 h. After this series of bi-reforming tests, TPO of the spent catalyst was carried out, which showed detectable but unquantifiable carbon deposition. The presence of steam in bi-reforming greatly limits carbon deposition compared to directly related dry-reforming tests on this same catalyst.
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| 6. |
- Kumar, N., et al.
(författare)
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Catalytic bi-reforming of methane : From greenhouse gases to syngas
- 2015
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Ingår i: Current Opinion in Chemical Engineering. - : Elsevier. - 2211-3398. ; 9, s. 8-15
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Tidskriftsartikel (refereegranskat)abstract
- The bi-reforming reaction to produce syngas from CH4 and CO2 offers significant advantages over dry reforming and oxy-CO2 with respect to catalyst deactivation by carbonization. This approach has potential for powerful new alternatives and is entering the stage of increasing advanced research toward commercialization of the technology. Research is ongoing to develop catalysts that are resistant to high temperatures and the presence of a more oxidative environment due to steam. All current research on bi-reforming catalysis is focused on Ni-based catalysts, a logical extension based on commercial materials on steam/methane reforming and dry reforming. However, recent work on thermally stable crystalline oxides has promise, particularly in resisting carbon deposition while remaining stable at the demanding conditions of bi-reforming.
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| 7. |
- Kumar, N., et al.
(författare)
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CO2 reforming of methane over Ni-based 6%LSNZ pyrochlore catalyst
- 2016
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Ingår i: 22nd International Congress of Chemical and Process Engineering, CHISA 2016 and 19th Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction, PRES 2016. - : Czech Society of Chemical Engineering. - 9781510859623 ; , s. 56-57
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Konferensbidrag (refereegranskat)
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| 8. |
- Rahmani, Mohammad, et al.
(författare)
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Deactivation of Oxidation Catalysts for VOC Abatement by Si and P Compounds
- 2004
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Ingår i: Catalysis Volume 17. - 9780854042296 ; , s. 210-257
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Bokkapitel (refereegranskat)abstract
- There is an increasing challenge for chemical industry and research institutions to find cost-efficient and environmentally sound methods of converting natural resources into fuels chemicals and energy. Catalysts are essential to these processes and the Catalysis Specialist Periodical Report series serves to highlight major developments in this area. This series provides systematic and detailed reviews of topics of interest to scientists and engineers in the catalysis field. The coverage includes all major areas of heterogeneous and homogeneous catalysis and also specific applications of catalysis such as NOx control kinetics and experimental techniques such as microcalorimetry. Each chapter is compiled by recognised experts within their specialist fields and provides a summary of the current literature. This series will be of interest to all those in academia and industry who need an up-to-date critical analysis and summary of catalysis research and applications. Catalysis will be of interest to anyone working in academia and industry that needs an up-to-date critical analysis and summary of catalysis research and applications.Specialist Periodical Reports provide systematic and detailed review coverage in major areas of chemical research. Compiled by teams of leading experts in their specialist fields, this series is designed to help the chemistry community keep current with the latest developments in their field. Each volume in the series is published either annually or biennially and is a superb reference point for researchers. www.rsc.org/spr
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| 9. |
- Elm Svensson, Erik, 1976-
(författare)
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Nanotemplated High-Temperature Materials for Catalytic Combustion
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Catalytic combustion is a promising technology for heat and power applications, especially gas turbines. By using catalytic combustion ultra low emissions of nitrogen oxides (NOX), carbon monoxide (CO) and unburned hydrocarbons (UHC) can be reached simultaneously, which is very difficult with conventional combustion technologies. Besides achieving low emission levels, catalytic combustion can stabilize the combustion and thereby be used to obtain stable combustion with low heating-value gases. This thesis is focused on the high-temperature part of the catalytic combustor. The level of performance demanded on this part has proven hard to achieve. In order to make the catalytic combustor an alternative to the conventional flame combustor, more stable catalysts with higher activity have to be developed. The objective of this work was to develop catalysts with higher activity and stability, suitable for the high-temperature part of a catalytic combustor fueled by natural gas. Two template-based preparation methods were developed for this purpose. One method was based on soft templates (microemulsion) and the other on hard templates (carbon). Supports known for their stability, magnesia and hexaaluminate, were prepared using the developed methods. Catalytically active materials, perovskite (LaMnO3) and ceria (CeO2), were added to the supports in order to obtain catalysts with high activities and stabilities. The supports were impregnated with active materials by using a conventional technique as well as by using the microemulsion technique. It was shown that the microemulsion method can be used to prepare catalysts with higher activity compared to the conventional methods. Furthermore, by using a microemulsion to apply active materials onto the support a significantly higher activity was obtained than when using the conventional impregnation technique. Since the catalysts will operate in the catalytic combustor for extended periods of time under harsh conditions, an aging study was performed on selected catalysts prepared by the microemulsion technique. The stability of the catalysts was assessed by measuring the activity before and after aging at 1000 C in humid air for 100 h. One of the most stable catalysts reported in the literature, LMHA (manganese-substituted lanthanum hexaaluminate), was included in the study for comparative purposes. The results showed that LMHA deactivated much more strongly compared to several of the catalysts consisting of ceria supported on lanthanum hexaaluminate prepared by the developed microemulsion method. Carbon templating was shown be a very good technique for the preparation of high-surface-area hexaaluminates with excellent sintering resistance. It was found that the pore size distribution of the carbon used as template was a crucial parameter in the preparation of hexaaluminates. When a carbon with small pores was used as template, the formation of the hexaaluminate crystals was strongly inhibited. This resulted in a material with poor sintering resistance. On the other hand, if a carbon with larger pores was used as template, it was possible to prepare materials with hexaaluminate as the major phase. These materials were, after accelerated aging at 1400 C in humid air, shown to retain surface areas twice as high as reported for conventionally prepared materials.
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| 10. |
- Gaur, Sarthak, et al.
(författare)
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Catalytic Activity of Titania-Supported Core-Shell Fe3O4@Au NanoCatalysts for CO Oxidation
- 2012
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 116:42, s. 22319-22326
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Tidskriftsartikel (refereegranskat)abstract
- In continuation of our previous work (J. Phys. Chem. Lett. 2010, 1(20), 3141 and J. Phys. Chem. C 2010, 114 (45), 19194), Fe3O4@Au core-shell types of nanoparticles were prepared by coating superparamagnetic iron oxide nanoparticles (SPIONS; similar to 4.9 nm) with a thin layer of gold (similar to 0.5 nm) and supported on microporous TiO2. To remove the ligands attached to nanoparticles, the catalyst was treated at 200, 300, 400, and 500 degrees C in either (a) a reducing atmosphere with H-2/Ar or (b) an oxidizing atmosphere with O-2/He. The synthesized nanoparticles and freshly prepared catalysts were characterized by HRTEM, which revealed that the size of the Fe3O4@Au nanoparticles was 5.34 +/- 0.71 nm and that of Fe3O4@Au/TiO2 was 5.96 +/- 0.71 nm. Fresh and pretreated programmed reduction, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. To test the activity of Fe3O4@Au/TiO2 catalysts, CO oxidation was performed over catalysts from 30 to 500 degrees C. Results showed that the catalyst treated with H-2/Ar at 500 degrees C had a lower light-off temperature and the highest CO conversion (similar to 68%) at 300 degrees C; however, such a treatment also resulted in catalyst sintering, leading to a net increase in particle size to 7.87 +/- 1.59 nm. The higher catalytic activity of the catalyst treated with H-2 at 500 degrees C can be attributed to the copresence of Fe-0 and Au-0 in the catalyst, the complete removal of organic ligands from the catalyst surface, and possibly the synergistic interaction between Au and Fe.
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| 11. |
- Karatzas, Xanthias
(författare)
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Rhodium diesel-reforming catalysts for fuel cell applications
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Heavy-duty diesel truck engines are routinely idled at standstill to provide cab heating or air conditioning, and in addition to supply electricity to comfort units such as radio and TV. Idling is an inefficient and unfavorable process resulting in increased fuel consumption, increased emissions, shortened engine life, impaired driver rest and health, and elevated noise. Hydrogen-fueled, polymer-electrolyte fuel-cell auxiliary power unit (PEFC-APU) as a silent external power supply, working independently of the main engine, is proposed as viable solution for better fuel economy and abatement of idling emissions. In a diesel PEFC-APU, the hydrogen storage problem is circumvented as hydrogen can be generated onboard from diesel by using a catalytic reformer. In order to make catalytic diesel PEFC-APU systems viable for commercialization research is still needed. Two key areas are the development of reforming catalyst and reformer design, which both are the scope of this thesis. For diesel-reforming catalysts, low loadings of Rh and RhPt alloys have proven to exhibit excellent reforming and hydrogen selectivity properties. For the development of a stable reforming catalyst, more studies have to be conducted in order to find suitable promoters and support materials to optimize and sustain the long-term performance of the Rh catalyst. The next step will be full-scale tests carried out at realistic operating conditions in order to fully comprehend the overall reforming process and to validate promising Rh catalysts. This thesis can be divided into two parts; the first part addresses the development of catalysts in the form of washcoated cordierite monoliths for autothermal reforming (ATR) of diesel. A variety of catalyst compositions were developed containing Rh or RhPt as active metals, CeO2, La2O3, MgO, Y2O3 as promoters and Al2O3, CeO2-ZrO2, SiO2 and TiO2 as support materials. The catalysts were tested in a bench-scale reactor and characterized by using N2-BET, XRD, H2 chemisorption, H2-TPR, O2-TPO, XPS and TEM analyses. The second part addresses the development and testing of full-scale reformers at various realistic operating conditions using promising Rh catalysts. The thesis shows that a variety of Rh on alumina catalysts was successfully tested for ATR of diesel (Papers I-IV). Also, zone-coating, meaning adding two washcoats on specific parts of the monolith, was found to have beneficial effects on the ATR catalyst performance (Paper II). In addition, RhPt supported on CeO2-ZrO2 was found to be one of the most active and promising catalyst candidates for ATR of diesel. The superior performance may be attributed to higher reducibility of RhiOx species and greater dispersion of Rh and Pt on the support (Paper IV). Finally, two full-scale diesel reformers were successfully developed and proven capable of providing high fuel conversion and hydrogen production from commercial diesel over selected Rh catalysts (Papers II-III, V-VI).
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| 12. |
- Pärnamets, Philip, et al.
(författare)
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Biasing moral decisions by exploiting the dynamics of eye gaze
- 2015
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 112:13, s. 4170-4175
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Tidskriftsartikel (refereegranskat)abstract
- Eye gaze is a window onto cognitive processing in tasks such as spatial memory, linguistic processing, and decision making. We present evidence that information derived from eye gaze can be used to change the course of individuals’ decisions, even when they are reasoning about high-level, moral issues. Previous studies have shown that when an experimenter actively controls what an individual sees the experimenter can affect simple decisions with alternatives of almost equal valence. Here we show that if an experimenter passively knows when individuals move their eyes the experimenter can change complex moral decisions. This causal effect is achieved by simply adjusting the timing of the decisions. We monitored participants’ eye movements during a two-alternative forced-choice task with moral questions. One option was randomly predetermined as a target. At the moment participants had fixated the target option for a set amount of time we terminated their deliberation and prompted them to choose between the two alternatives. Although participants were unaware of this gaze-contingent manipulation, their choices were systematically biased toward the target option. We conclude that even abstract moral cognition is partly constituted by interactions with the immediate environment and is likely supported by gaze-dependent decision processes. By tracking the interplay between individuals, their sensorimotor systems, and the environment, we can influence the outcome of a decision without directly manipulating the content of the information available to them.
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| 13. |
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| 14. |
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| 15. |
- Pärnamets, Philip, et al.
(författare)
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Changing minds by tracking eyes: Dynamical systems, gaze and moral decisions
- 2013
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Ingår i: Proceedings of the 35th Annual Conference of the Cognitive Science Society.
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Konferensbidrag (refereegranskat)abstract
- Decision making is a dynamic process. Alternatives compete over time, and this competition plays out in sensorimotor processes. This is true not just for perceptual decisions or simple categorisation tasks, but also for moral decisions, which are the outcome of a complex interplay of intuition, emotion and reasoning. In this experiment, we first establish a descriptive and causal link between gaze and moral judgement. We then use eye movements to track the time course of participants’ moral decisions and show that by interrupting their decision process based on their gaze position, we are able to influence what they decide. We interpret this as evidence for a dynamical systems view of decision making and argue that our results provide new insights into how judgements are reached and constructed in our embodied minds.
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