FT-IR AND EPR SPECTROSCOPIC ANALYSIS OF LA1-XCEXCOO3 PEROVSKITE-LIKE CATALYSTS FOR NO REDUCTION BY CO

A FT-IR and EPR spectroscopic investigation has been carried out on a series of La1-xCexCoO3 (x=0-0.15) perovskite-type catalysts, which are quite active for the reduction of NO by CO, and a mechanism has been proposed for this reaction. The first step involves the oxidation of C O by the catalyst, followed by the dissociative adsorption of NO onto the catalyst surface. Finally, adsorbed nitrogen (N-ads) yields N2O, N -2 and NCOads along three parallel paths. Thus, oxygen exchange betwee n NO and CO seems to occur indirectly and involves a surface oxygen va cancy. The catalytic activity is decreased by the substitution of Ce4 for La3+ in the perovskite-type structure, which reduces the mobility of bulk oxygen. Activity is partially restored for x greater than or equal to 0.05 due to the presence of a segregated cerium oxide phase.