Electrochemical promotion of bimetallic Rh-Ag/YSZ catalysts for the reduction of NO under lean burn conditions

WILLIAMS, F J; MACLEOD, N; TIKHOV, M S; LAMBERT, R M

ELECTROCHIMICA ACTA

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2002 vol. 47 p. 1259 - 1265

0013-4686

At positive overpotentials, Rh-Ag bimetallic electrodes interfaced with yttria-stabilised zirconia (YSZ) exhibit strong electro- chemical promotion in the catalytic reduction of NO by propene, even in the presence of a large excess of gaseous oxygen. Compared with the unpromoted system, at positive overpotentials, the N2 production rate can be accelerated by a factor of eight: this is the key figure of merit. In addition the N2 selectivity improves from 28 to 55%. The effect on reaction rates is strongly non-faradaic and persists to a significant degree in the absence of applied potential. At negative overpotentials the nitrogen-con- taining products exhibit faradaic behaviour, possibly reflecting self-poisoning of the system due to excessive adsorption of oxygen. The overall performance of the Rh􏱇Ag/YSZ bimetallic system is substantially better than that of Rh/YSZ, suggesting that the former are promising candidates for use in novel approaches to NOx reduction under fuel lean conditions. © 2002 Elsevier Science Ltd. All rights reserved.