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.
