Catalytic performance of Ir/CeO 2 for NO–C 3H 6–O 2 reaction in a stoichiometric condition

Abstract

Supported iridium catalyst was found to be highly active for NO reduction with C 3H 6 in a stoichiometric condition. Among the supported iridium catalysts tested here, Ir/CeO 2 showed the highest activity. In order to examine the influence of CeO 2 support on the catalytic performance of supported iridium, we prepared CeO 2 by precipitation method using different cerium precursors. Iridium catalyst supported on CeO 2 prepared by using Ce(IV) precursor (Ce(NH 4) 2(NO 3) 6) showed higher activity for NO reduction with C 3H 6 than that by using Ce(III) precursor (Ce(NO 3) 3·6H 2O), although the former catalyst has low BET surface area and low iridium dispersion. The activity of iridium catalyst supported on CeO 2, which was prepared by using Ce(III) precursor, calcined at different temperature was also found to increase with increasing the calcination temperature of CeO 2 support. The low activity of iridium catalyst supported on CeO 2 calcined at 600 °C was considered to be due to a strong metal support interaction (SMSI) effect by the reaction gas treatment at 600 °C, resulting in the formation of less active Ir–CeO 2 interacting species. On the other hand, the use of CeO 2 calcined at higher temperatures was found to be important to obtain a catalytically active iridium species under the stoichiometric reaction condition.