Abstract: A series of Pt/Ce_xZr_1-xO₂ catalysts were prepared by the wet-impregnation method, characterized by X-ray diffraction and tem-perature-programmed reduction, and tested in the water gas shift (WGS) reaction. The results show that the Ce_xZr_1-xO₂ solid solution has higher redox ability, and doping ceria with zirconium apparently changes the pore structure. The Pt catalysts supported on Ce_xZr_1-xO₂ has higher Pt dispersion and WGS activity in pure reforming syngas. The WGS activity dropped in sulfur-containing syngas over the Pt/Ce_xZr_1-xO₂ catalysts. The loss of activity increases with the increase of H₂S content, but the deactivation of the catalyst due to H₂S adsorp-tion is reversible and can be readily reversed in the reducing atmosphere of the WGS mixture without H2S.

Key words: water gas shift, cerium, zirconium, solid solution, redox ability, platinum, hydrogen sulfide, reversible poisoning