Activity of Rhx+Species in CO Oxidation and NO Reduction in a CO/NO/O2Stoichiometric Mixture over a Rh/CeO2-ZrO2Catalyst
Activity of Rhx+Species in CO Oxidation and NO Reduction in a CO/NO/O2Stoichiometric Mixture over a Rh/CeO2-ZrO2Catalyst
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Rhx 物种在 Rh/CeO2-ZrO2 催化剂上 CO/NO/O2 化学计量混合物中 CO 氧化和 NO 还原的活性
DOI：
10.1006/jcat.1998.2222
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
G. Djéga
中科院分区：
文献类型：
--
作者：
F. Fajardie;J. Tempère;J. Manoli;O. Touret;G. Blanchard;G. Djéga
The catalytic activity of a 0.30 wt% Rh/CeO{sub 2}-ZrO{sub 2} catalyst (25% ZrO{sub 2} in weight) 188 m{sup 2}/g was studied in the oxidation of CO and reduction of NO in a CO/NO/O{sub 2} stoichiometric mixture, in the temperature range of 298--773 K. The hydrogenation of benzene, a structure insensitive reaction was used for counting surface Rh(0) atoms after either thermal treatment of the catalyst in hydrogen at 773 K, or reduction by the stoichiometric CO/O{sub 2}/NO reaction mixture. The bibliography shows that the turnover rate over RH{sup x+} is lower than that over Rh(0) by two orders of magnitude. Rhodium supported on CeO{sub 2}-ZrO{sub 2} submitted to the above reducing treatments was found to be totally inactive in benzene hydrogenation but active in CO/NO/O{sub 2} reaction. As a conclusion the present catalyst consisted exclusively of Rh{sup x+} surface species. The catalyst behavior of this rhodium-supported catalyst was interpreted in terms of multiple active sites containing one Rh{sup x+} ion grafted in the support and able to chemisorb CO and/or NO as for a rhodium homogeneous complex. This Rh{sup x+} is associated with two adjacent oxygen vacancies (and corresponding Ce{sup 3+} cations) linked to the reduction of the support andmore » permitting oxygen and NO chemisorption. A method was defined for counting surface Rh{sup x+} containing multiple sites by measuring the number of NO molecules adsorbed at low temperature and desorbing at the temperature of light-off of CO. A (NO/Rh{sup x+}) ratio of 2 was found, in agreement with a dinitrosyl species reaction intermediate.« less
The catalytic activity of a 0.30 wt% Rh/CeO{sub 2}-ZrO{sub 2} catalyst (25% ZrO{sub 2} in weight) 188 m{sup 2}/g was studied in the oxidation of CO and reduction of NO in a CO/NO/O{sub 2} stoichiometric mixture, in the temperature range of 298--773 K. The hydrogenation of benzene, a structure insensitive reaction was used for counting surface Rh(0) atoms after either thermal treatment of the catalyst in hydrogen at 773 K, or reduction by the stoichiometric CO/O{sub 2}/NO reaction mixture. The bibliography shows that the turnover rate over RH{sup x+} is lower than that over Rh(0) by two orders of magnitude. Rhodium supported on CeO{sub 2}-ZrO{sub 2} submitted to the above reducing treatments was found to be totally inactive in benzene hydrogenation but active in CO/NO/O{sub 2} reaction. As a conclusion the present catalyst consisted exclusively of Rh{sup x+} surface species. The catalyst behavior of this rhodium-supported catalyst was interpreted in terms of multiple active sites containing one Rh{sup x+} ion grafted in the support and able to chemisorb CO and/or NO as for a rhodium homogeneous complex. This Rh{sup x+} is associated with two adjacent oxygen vacancies (and corresponding Ce{sup 3+} cations) linked to the reduction of the support andmore » permitting oxygen and NO chemisorption. A method was defined for counting surface Rh{sup x+} containing multiple sites by measuring the number of NO molecules adsorbed at low temperature and desorbing at the temperature of light-off of CO. A (NO/Rh{sup x+}) ratio of 2 was found, in agreement with a dinitrosyl species reaction intermediate.« less