NEW INSIGHTS ON THE MECHANISM OF THE NO REDUCTION WITH CO OVER ALUMINA-SUPPORTED COPPER-CATALYSTS

Carbon monoxide (CO) and nitric oxide (NO) are among the major components of exhaust gases produced from vehicle engines and industrial boilers. Apart from noble metals (Rh, Pt, Pd,...), which are very active for the simultaneous NO reduction and CO oxidation, copper based catalysts have been widely studied as less expensive alternatives for this reaction. Here we use ''in situ'' X-ray absorption near edge structure (XANES) to study the state of copper species during the NO + CO reaction. The correlation of copper surface species present on the catalyst with its catalytic performance allows us to deduce that a redox-type mechanism (Cu2+/Cu+) is working under reaction conditions and that the NO adsorption and/or dissociation is the slow step of the reaction.