Effect of Pd deposition procedure on activity of Pd/Ce0.5Sn0.5O2 catalysts for low-temperature CO oxidation

Abstract Two methods for the preparation of Pd/Ce 0.5 Sn 0.5 O 2 catalysts have been used: solution combustion (SC) of Pd, Ce and Sn precursor mixtures, and incipient wetness impregnation by [Pd(NO 3 ) 2 (H 2 O) 2 ] solution of Ce 0.5 Sn 0.5 O 2 – δ support, obtained by the SC technique (SC + IWI). The formation of metallic palladium was observed in addition to ionic palladium in a Pd x (Ce 0.5 Sn 0.5 ) 1 – x O 2 – x – δ solid solution due to high-temperature Pd precursor decomposition during the SC process. IWI of Ce 0.5 Sn 0.5 O 2 – δ support has been demonstrated to lead to a uniform solid solution of Pd 2 + ions in the Ce 0.5 Sn 0.5 O 2 – δ matrix at 1% Pd content that resulted in high catalyst activity towards CO oxidation. The increase of Pd content to 5% showed no influence on catalytic activity. This observation is explained by the formation of low active PdO species when Pd content is more than 1%. The proposed SC + IWI method allows obtaining highly active Pd/Ce 0.5 Sn 0.5 O 2 catalysts with low palladium content.