期刊
CATALYSIS TODAY
卷 158, 期 3-4, 页码 481-489出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.cattod.2010.07.020
关键词
Dynamic oxygen storage capacity; Water-gas shift; Steam reforming; Turnover frequency; Compensation effect
资金
- Program of New Century Excellent Talents in University [NCET-06-0243]
- Natural Science Foundation of China [50972104]
- Program of Introducing Talents of Discipline to Universities of China [B06006]
The catalytic performances of Pd/CeO(2), Pd/Ce(0.67)Zr(0.33)O(2), and Pd/Ce(0.67)Zr(0.33)O(2)-Al(2)O(3) three-way catalysts are evaluated through dynamic oxygen storage pulses (DOSC), water-gas shift reactions (WGS), and steam reforming reactions (SR). Despite the differences in the morphologies and chemical compositions of the catalysts, the very similar mechanisms over the three samples for the above reactions have been confirmed according to the compensation effect. Oxygen migration ability plays a key role in DOSC activities. The dynamic oxygen storage rates (DOSR) are ordered as: Pd/Ce(0.67)Zr(0.33)O(2)-Al(2)O(3) > Pd/Ce(0.67)Zr(0.33)O(2) > Pd/CeO(2). The synergetic effect of ceria contents, oxygen vacancies, and precious metal dispersion determines the activity of WGS reaction. The orders of light-off temperatures are as follows: WGS-fresh: Pd/CeO(2) < Pd/Ce(0.67)Zr(0.33)O(2)-Al(2)O(3) < Pd/Ce(0.67)Zr(0.33)O(2); WGS-aged: Pd/Ce(0.67)Zr(0.33)O(2)-Al(2)O(3) < Pd/CeO(2) < Pd/Ce(0.67)Zr(0.33)O(2). For SR reactions, oxidized states of palladium particles and less acidity of support oxides can be beneficial. Thus the light-off temperatures are ordered as: SR-fresh: Pd/Ce(0.67)Zr(0.33)O(2) < Pd/CeO(2) < Pd/Ce(0.67)Zr(0.33)O(2)-Al(2)O(3); SR-aged: Pd/CeO(2) < Pd/Ce(0.67)Zr(0.33)O(2)-Al(2)O(3) < Pd/Ce(0.67)Zr(0.33)O(2). (C) 2010 Elsevier B. V. All rights reserved.
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