Effects of the structure of ceria on the activity of gold/ceria catalysts for the oxidation of carbon monoxide and benzene

Using precipitated cerium hydroxide dried at 100 °C as the support, highly dispersed ceria-supported gold catalyst was prepared. Compared with similarly prepared catalysts supported on low-surface area ceria, gold on the high-surface area support showed more resistance to sintering and was more active toward the oxidation of CO and benzene. The oxidation of benzene was very dependent on the structure of ceria. Temperature-programmed reduction showed that the reducibility of surface oxygen was higher for high-surface area ceria. It is proposed that the creation of surface oxygen vacancies by ceria surface reduction promoted oxygen adsorption. Active oxygen formed by dissociation of the adsorbed oxygen is the active species for benzene oxidation, and the dissociation is promoted by gold nanoparticles. When present together in the reactant mixture, benzene inhibited the oxidation of CO, but CO enhanced the oxidation of benzene. Moisture had a promoting effect on both CO and benzene oxidation.