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低温度的高效催化由电场辅助制氢系统

2018-4-22 09:57| 发布者: dymodel| 查看: 94| 评论: 0|原作者: mind

摘要: 靖关根*,原口正幸,富冈彦,松方和荣一彦菊池 应用化学系,早稻田大学, 3-4-1 ,大久保,新宿,东京,日本169-8555 开销。化学。一, 2010, 114 ( 11),页3824-3833 个人主页: 10.1021/jp906137h 出版日期( ...
靖关根*,原口正幸,富冈彦,松方和荣一彦菊池
应用化学系,早稻田大学, 3-4-1 ,大久保,新宿,东京,日本169-8555
开销。化学。一, 2010, 114 ( 11),页3824-3833
个人主页: 10.1021/jp906137h
出版日期(网络) : 2009年9月18日
版权所有© 2009年美国化学学会
专刊部的“绿色能源生产的化学研讨会“ 。*通讯作者。电话和传真: +81-3-5286-3114。电子邮箱: ysekine@waseda.jp.

低温度的高效催化由电场辅助制氢系统

我们调查了一个电场,以促进催化活性催化反应的协助4 ,我们可以实现在一个氢,低温生产有效的进程,例如423 k.在电场的存在,四乙醇蒸汽重整反应,乙醇分解,水煤气变换和蒸汽重整甲烷着手在非常低的温度,如423 K,这里传统的催化反应难以进行。反应物转化大大提高了电场,并为这4个反应的表观活化能是由电气领域中的应用降低。这个过程可以通过使用产生了相当小的氢气和合成气能源需求,并快速反应。
真假难辨。


原文如下:

Low-Temperature Hydrogen Production by Highly Efficient Catalytic System Assisted by an Electric Field
Yasushi Sekine*, Masayuki Haraguchi, Masahiko Tomioka, Masahiko Matsukata and Eiichi Kikuchi
Department of Applied Chemistry, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo, 169-8555 Japan
J. Phys. Chem. A, 2010, 114 (11), pp 3824–3833
DOI: 10.1021/jp906137h
Publication Date (Web): September 18, 2009
Copyright © 2009 American Chemical Society
† 
Part of the special issue “Green Chemistry in Energy Production Symposium”., * Corresponding author. Phone and Fax: +81-3-5286-3114. E-mail: ysekine@waseda.jp
Abstract
 
We investigated four catalytic reactions assisted with an electric field to promote catalytic activity, and we could achieve an effective process for hydrogen production at low temperatures, such as 423 K. In the presence of the electric field, four reactions of steam reforming of ethanol, decomposition of ethanol, water gas shift, and steam reforming of methane proceeded at very low temperature, such as 423 K, where a conventional catalytic reaction hardly proceeded. Conversion of reactant was greatly increased by the electric field, and apparent activation energies for these four reactions were lowered by the application of the electric field. This process can produce hydrogen and syngas by using a considerably small energy demand and has quick response.

另一篇文章如下:

Clean Hydrogen Production Using Low Temperature Water Gas Shift Catalysis
C. Hardacre,1,* J. Breen,1 R. Burch,1 Y. Chen,1 A. Goguet,1 F. Meunier,1 P. Hu,1 R.W. Joyner,1 B.S. Mun,2 R. Pilamsombat,1 D. Thompsett,3 D. Tibiletti1
1CenTACat/School of Chemistry and Chemical Engineering, Queen’s University, Belfast BT9 5AG, UK; 2ALS, Berkeley Lab,1 Cyclotron Rd, Berkeley, USA; 3JMTC, Blounts Court, Sonning Common, Reading RG4 9NH, UK; 
*c.hardacre@qub.ac.uk

Recent results on Au supported on CeO2 , , ,  have displayed promising results for the WGS reaction, however, there is a difficulty in preparing highly active gold catalysts which do not deactivate.  For these systems the deactivation has been associated with the formation of carbonates  or formates,  and the loss of oxide surface area.  However, there has been no consensus, to date. The present paper reports on the use of in situ EXAFS, DRIFTS, high pressure XPS coupled with DFT calculations to elucidate the deactivation mechanism of highly active Au/CeZrO4 catalysts for low temperature WGS and a method of stabilising the activity.
Excellent low temperature WGS activity was found for the 2% Au/CeZrO4 catalysts with the equilibrium conversion reached at ~200oC. However, on increasing the WGS reaction temperature above 250oC, significant deactivation was observed with the temperature for 50% conversion rising from 140oC to 220oC. A similar decrease in activity was also observed if the temperature was maintained at 200oC with the catalyst showing a gradual deactivation over a period of 30 h. The rate of deactivation was determined by the water content and under high humidity (>10% water) rapid loss of activity was found. EXAFS of the fresh catalyst showed that the local structure around the gold is dominated by the presence of oxygen co-ordination at ~ 2 Å which is consistent with bond distances found in a gold oxide.  Additional features at 3-4 Å were also found and were fitted to cerium co-ordination in the second shell.  Under the WGS reaction conditions, the in-situ EXAFS showed that the gold transforms into Au0 state forming metallic clusters of ~ 50 atoms.  Importantly, despite the change in activity of the catalyst on thermal cycling no agglomeration of the metal particles was observed and the 1st shell co-ordination remained at ~ 6. 
High pressure XPS on the 2% Au/CeZrO4 catalyst under reaction conditions at 150 oC and 300oC also showed the presence of Au0 in good agreement with the XANES.  However, at higher temperature a decrease in intensity of the gold 4f XPS peaks was observed.  In-situ DRIFTS studies also indicated that the Au0 is where the CO adsorbs.  Under WGS conditions a single band at 2096 cm-1 was found assigned to a CO-Au0 species.  This feature is found to reduce in intensity with increasing reaction time. Both thermal and hydrothermal deactivation mechanisms are thought to be the result of the Au particle dewetting and the loss of metal-support interaction.  This is in excellent agreement with DFT results which indicate that the presence of surface hydroxyl groups destabilise gold clusters and that, even in the absence of hydroxyls, the gold cluster-support interaction is less favourable than gold-gold interactions.  Although the thermal deactivation is not affected, on stream deactivation may be reduced by pre-treating the catalyst in the full WGS mix and then switching to a CO2 free feed.

References

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[1]A. Amieiro Foncesca, J. Fisher, D. Thompsett, unpublished results.
[1]D Tibiletti, A Amieiro-Fonseca, R Burch, Y Chen, JM Fisher, A Goguet, C Hardacre, P Hu, D Thompsett, J. Phys. Chem. B 109 (2005) 22553.
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