The Catalytic Performance Of Cu-Zn And Pt-Co Catalysts For Water Gas Shift Reaction

The water gas shift?WGS?reaction is a process that CO reacts with H₂O to produce H₂ and CO₂.It can be applied in the polymer electrolyte membrane fuel cell to remove the small amount of CO and produce isometric H₂.From a thermodynamic view point,the WGS reaction is an exothermic reaction.Thus,the low temperature is more beneficial to the reaction.However,the reaction rate is slower at low temperature which was limited by the kinetics.Therefore,it is significant to explore the active catalysts for the low temperature WGS reaction.In this paper,Cu-Zn catalysts were prepared with step-precipitation?SP?method,in comparison with other methods,such as co precipitation?CP?,deposition precipitation?DP?and homogeneous precipitation?HP?.The WGS activity of the catalysts was investigated after calcination in air at 400 ^oC.It can be seen that the catalyst with SP method exhibits much higher activity than that with other methods especially at lower temperatures?<240 ^oC?.The structures of various catalysts were characterized by XRD,TEM and HRTEM,XPS,and H₂-TPR.The results suggest that the catalytic activity may be relative to particle size,highly dispersed surface CuO with contact to ZnO and the surface chemisorbed oxygen species.Besides,the influence of Co addition on the WGS activity of Pt/CeO₂ catalyst was studied.Pt-Co/CeO₂ catalysts were prepared with co-impregnation method,in which the Co amount is 0.1%,0.2%,and 0.4%respectively.The WGS reactivity was investigated after catalysts treated with different conditions.The results reveal that the Co addition can significantly improve the activity of the Pt/CeO₂ catalyst when air was used as the pretreatment gas.The catalysts treated in air at 400 ^oC were characterized by XRD,TEM and HRTEM,XPS,and H₂-TPR.These results show that the Co addition may influence the interaction between Pt and CeO₂,resulting in the better activity.