Effect of Ag doping on Pd/Ag-CeO 2 catalysts for CO and C 3 H 6 oxidation

To achieve high fuel efficiency and low emission in automobiles, it is necessary to develop highly active diesel oxidation catalysts (DOCs). Pd/CeO catalysts have been widely used as active catalysts for CO and C H oxidation reactions. Additionally, Ag has been reported to enhance the oxygen storage capacity (OSC) of CeO , which contributes to the oxidation ability of Pd/CeO . In this study, Pd/Ag-CeO catalysts were used for CO and C H oxidation reactions. When CeO was doped with appropriate amounts of Ag, reducibility and CO desorption rate were increased, which confirmed the high OSCs of Ag-doped catalysts. However, Ag particles were formed and the Ce /Ce ratio decreased when CeO was doped with excess amounts of Ag. In addition, reduced Pd (Pd ), which is an active species for C H oxidation, was formed and maintained even under oxidative reaction conditions. Since the removal of C H is important for the oxidation of CO and C H , the catalyst with the highest Pd fraction (Pd/0.1Ag-CeO and Pd/0.3Ag-CeO ) presented improved catalytic activity. Consequently, the optimal amount of Ag enhanced the OSC of Pd/Ag-CeO catalysts and formed active Pd species under oxidative conditions, which resulted in the excellent catalytic activity of Pd/Ag-CeO for the CO and C H oxidation reaction.