The positive role of Ir0 and OV on the reduction of SO2 by CO over Ir/CeO2

Abstract

Several Ir/CeO2 catalysts were synthesized with different preparation variable, the variable influences the SO2 reduction by CO over Ir/CeO2 catalyst through changing the specific surface area, the content of Ir0 species and the concentration of oxygen vacancies on the surface of catalysts. The characteristic results showed that the as-prepared Ir/CeO2-6 catalyst has the highest crystallinity, the smallest grain size and the largest lattice parameter among the synthesized catalysts. All these three catalysts are mesoporous structures, and Ir/CeO2-6 has the largest pore size and specific surface area. DFT results showed that the adsorption energies of CO and SO2 at higher Ir loading is consistent with the stoichiometric ratio. Combining the results of Raman, XPS and H2-TPR, Ir/CeO2-6 has the highest Ce3+ content, OVs content and Ir0 content which exhibited the strongest Ir-O-Ce interaction and caused better catalytic activity. All the as-prepared catalysts follow the redox mechanism during reactions. This study illustrates the preparation method affecting microstructure and then the reaction activity, providing research ideas for modulating the preparation of efficient CeO2-based catalyst for SO2 reduction by CO.