Abstract: Au-Pt/CeO2 catalyst samples modified with alkali metals M (M = Na, K, Rb, and Cs) were prepared and their catalytic activity for water-gas shift (WGS) was evaluated. The structure and surface properties of the Au-Pt/CeO2 catalyst promoted by potassium were investigated by X-ray powder diffraction, H2 temperature-programmed reduction, ultraviolet-visible diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. The higher activity obtained on the K-promoted Au-Pt/CeO2 sample was possibly due to the reduction of Au3+ species and the enrichment of Ce3+ on the catalyst surface, which generated more oxygen vacancies. The catalytic activity of Au-Pt/CeO2 was greatly influenced by the alkali metals. When the K content was 0.025%, the CO conversion achieved up to 95% at 250 oC.

Key words: ceria, platinum, gold, potassium, promoter, water-gas shift