Promotion of low-temperature oxidation of CO over Pd supported on titania-coated ceria

Abstract

The design of a metal oxide support for Pd was investigated to promote the oxidation of CO at lower temperatures. Through a screening study using pure metal oxides, Pd/CeO₂ showed the highest activity above 100 °C, while homemade TiO₂ was more effective below 100 °C as a support for Pd. Applying the advantages of CeO₂ and TiO₂, we proposed a TiO₂–CeO₂ support having a monolayer amount of surface TiO₂ supported on CeO₂. The Pd/TiO₂–CeO₂ catalyst showed higher activity than both Pd/TiO₂ and Pd/CeO₂, which was not achieved by using the CeO₂–TiO₂ mixed-oxide. The light-off temperature over Pd/TiO₂–CeO₂ was 100 °C lower than Pd/Al₂O₃. The effect of surface TiO₂ was attributed to the promotion of the reduction–oxidation cycle of supported Pd.