Effect of Thermal Aging on Local Structure and Three-Way Catalysis of Cu/Al2O3

Abstract

Cu supported on Al2O3, prepared by impregnation, was thermally aged at different temperatures, and the influence of thermal aging on the local structure, redox behavior of Cu, and catalytic activity for a stoichiometric NO–CO–C3H6–O2 reaction was investigated. Crystalline CuO was mainly formed on Al2O3 after thermal aging at ≤700 °C, whereas aging at higher temperatures induced Cu2+ incorporation into tetrahedral (Td-Cu2+) rather than octahedral (Oh-Cu2+) sites of γ-Al2O3. Despite its lower surface area, thermally aged Cu/Al2O3 with Td-Cu2+ sites showed higher catalytic performance for the stoichiometric NO–CO–C3H6–O2 reaction compared with the as-prepared catalyst, especially for NO reduction. Td-Cu2+ was reduced to Td-Cu+ during reaction with CO and/or C3H6, and NO could be reduced in subsequent reoxidation of Td-Cu+ to Td-Cu2+ by NO. This redox behavior is more probable on Td-Cu rather than crystalline CuO, resulting in enhancement of NO reduction during the three-way catalyst reaction.