N2O as an intermediate for the formation of N-2 during SCR (NO): stationary and transient conditions

Platinum-based catalysts can be used for the selective reduction of NOx in lean burn conditions, but they form undesirably high quantities of N2O. In this study conducted under stationary and transient conditions, we attempte d to better understand the mechanism of SCR (NO) over Pt. Me found that N-2 selectivity increased with contact time, that significant quantities of N- 2 were formed when N2O was used as the reactant, and that N2O was formed mo re quickly than N-2 when NO was used as the reactant. These results led us to propose a kinetic model in which adsorbed N2O is an intermediate for NO reduction into N-2. (C) 2000 Academie des sciences Editions scientifiques e t medicales Elsevier SAS.