Au/PO43−/TiO2 and PO43−/Au/TiO2 catalysts for CO oxidation: Effect of synthesis details on catalytic performance Original Research Article

Supported gold catalysts are active for CO oxidation, but the high-temperature deactivation is a shortcoming that may constrain their applications. Herein, we attempted to address this problem by using phosphate-doped Au/TiO2 synthesized via two routes. In route I, Au/PO43−/TiO2 catalysts were prepared by treating TiO2 (Degussa P25) with diluted H3PO4, followed by loading gold via deposition-precipitation. In route II, PO43−/Au/TiO2 catalysts were prepared by treating H2-reduced Au/TiO2 with diluted H3PO4. These catalysts were systematically pretreated at 200 or 500 °C before reaction testing. The overall CO conversion on 200 °C-pretreated Au/PO43−/TiO2 or PO43−/Au/TiO2 was always lower than that on 200 °C-pretreated Au/TiO2. However, the advantage of the phosphate addition became apparent after thermal treatment at a higher temperature. Both Au/PO43−/TiO2 and PO43−/Au/TiO2 pretreated at 500 °C retained significant activities at room temperature, whereas 500 °C-pretreated Au/TiO2 lost its activity. Control experiments and catalyst characterization were performed to investigate the impact of synthesis details on catalytic performance.