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 (¹⁰⁷Ag²⁺ and ¹⁰⁹Ag²⁺) 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⁺/Ag⁰, and Ag⁺/Ag⁰.