Model Ag/CeO2 catalysts for soot combustion: Roles of silver species and catalyst stability

Abstract

Ag/CeO2 has been regarded as a promising recipe for soot catalytic combustion in gasoline particulate filters, while lots of information about its reaction mechanism and practicability is yet missing. In this work, the reducibility and activity of three Ag/CeO2 model catalysts with different types of silver species (Agn+ nanoclusters, metallic Ag nanoclusters and metallic Ag nanoparticles) supporting on CeO2 nanorods were studied. It was suggested that silver facilitated the generation of Oxn- via Ag+-(Ce3+-VO)-induced O2 activation or ceria bulk-to-surface oxygen migration, both of which resulted in boosted soot combustion. From a practical point of view, the thermal ageing-induced silver sintering could be alleviated by the defective sites on CeO2, though certain degree of catalyst deactivation was still inevitable.