Investigation on catalytic oxidation of CO over Mo-Sn catalysts

A series of Mo-Sn catalysts with different Mo/Sn molar ratios were prepared by precipitation impregnation method. CO oxidation reaction was used as a probe reaction to investigate the effect of different Mo contents on the catalytic performance of CO oxidation, and further study the active center and structure-activity relationships of the catalysts. The results showed that the Mo1Sn20 catalyst achieved complete conversion of CO at 300°C, which was 50°C lower than that of pure SnO2. XRD, Raman, XPS, H2-TPR and in-situ FT-IR were used to analyze the crystal structure, valence state of molybdenum species, and redox properties of the catalysts. Compared with pure SnO2 catalyst, when a lower content of Mo species is introduced, the increase in specific surface area of Mo1Sn20 catalyst provides more active sites for the reaction. The enhanced interaction between Mo and Sn leads to the partial transformation of MoO3 to MoOx, producing more Mo5+ species. The presence of Mo5+ species promotes the adsorption activation of oxygen as well as the migration of oxygen atoms. The synergistic effect of lattice oxygen and Mo5+ species enhances the catalytic performance of the CO.