Physicochemical characterization and catalytic performance of 10% Ag/CeO2 catalysts prepared by impregnation and deposition-precipitation

Two silver-cerium oxide samples (Ag 10 wt.%) were prepared by two different methods: impregnation and deposition-precipitation. The XRD, EPR, XPS, and TPR techniques were used for physicochemical characterization. Catalysts were tested in C3H6, CO, and carbon black oxidation reactions. The impregnated catalyst showed better performance compared to the one prepared by deposition-precipitation in the different reactions. The EPR technique allowed the identification of three different Ag2+ sites in the impregnated solid along with the distinction of the Ag2+ isotopes (Ag-107(2+) and Ag-109(2+)) ions. The impregnated catalyst reduced at lower temperatures compared to the one prepared by deposition-precipitation. The catalytic activity of the impregnated solid was attributed to the presence of Ag2+ species that enhance the redox potential of the solid by creating three different redox couples: Ag2+/Ag+, Ag2+/Ag-0, and Ag+/Ag-0. (C) 2014 Elsevier Inc. All rights reserved.