Reduction of NO by CO over Rh/CeO2-ZrO2 catalysts -: Evidence for a support-promoted catalytic activity

被引:132
作者
Fornasiero, P
Rao, GR
Kaspar, J
L'Erario, F
Graziani, M
机构
[1] Univ Trieste, Dipartimento Sci Chim, I-34127 Trieste, Italy
[2] Indian Inst Technol, Dept Chem, Catalysis Sect, Madras 600036, Tamil Nadu, India
关键词
exhaust catalysts; rhodium; CeO2-ZrO2 solid solutions; CeO2-ZrO2 mixed oxides; NO reduction; CO oxidation; oxygen storage; temperature programmed reduction; redox properties;
D O I
10.1006/jcat.1998.1999
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Reduction of NO by CO catalysed by Rh/CeO2-ZrO2 solid solutions is investigated with the aim to elucidate the role of the CeO2-ZrO2 supports in modifying the activity of supported Rh. Two distinct kinetic regimes, characterised by different activation energies are observed below and above 500 K. It is proposed that below 500 K the reduction of NO occurs at the expenses of a concomitant oxidation of Ce3+ sites. In this model, the supported metal activates the reducing agent favouring the efficiency of Ce4+/Ce3+ redox couple. The influence of a high temperature reduction (H-2, 1073 K) is also investigated. Such a treatment, which increases the reducibility at low temperatures of the CeO2-ZrO2 solid solution, promotes the efficiency of the catalysts at low temperatures, confirming the important role of the Ce4+/Ce3+ redox couple in determining the activity of the catalyst. (C) 1998 Academic Press.
引用
收藏
页码:269 / 279
页数:11
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