A comparison of sodium-modified Rh/γ-Al2O3 and Pd/γ-Al2O3 catalysts operated under simulated TWC conditions

被引：37

作者：

Macleod, N ^{[1
]}

Issac, J ^{[1
]}

Lambert, RM ^{[1
]}

机构：

[1] Univ Cambridge, Dept Chem, Cambridge CB2 1EW, England

来源：

APPLIED CATALYSIS B-ENVIRONMENTAL | 2001年 / 33卷 / 04期

基金：

英国工程与自然科学研究理事会;

关键词：

NO; rhodium; palladium; sodium; N2O; selectivity; fuel rich; fuel lean;

D O I：

10.1016/S0926-3373(01)00191-6

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：

Addition of Na to Rh/gamma -Al2O3 and Pd/gamma -Al2O3 catalysts operated under identical simulated TWC conditions has dramatically different effects in the two cases (although the two metals respond similarly to Na promotion of NOx reduction in the absence of gaseous oxygen). Na addition to rhodium has a detrimental effect as manifested by severe poisoning and decreased nitrogen selectivity over the greater part of the temperature range studied. In contrast, Na promotion significantly improves the overall performance of Pd/gamma -Al2O3 catalysts under simulated TWC conditions. This is manifested by a considerable widening of the gas composition window over which palladium delivers high NOx conversion, whilst at the same time exhibiting markedly improved selectivity towards N-2 formation. The very different behaviour of the two metals may be understood in terms of a single underlying effect, namely, the electronic influence of sodium ions on the adsorption strength (and hence relative coverages) of the various reactants on the metal surface. ((C) 2001 Elsevier Science B.V. All rights reserved.

引用

页码：335 / 343

页数：9

共 29 条

[1] ENVIRONMENTAL CATALYSIS [J].