Catalytic oxidation of CO over Pt/TiO2 with low Pt loading: The effect of H2O and SO2

Anatase TiO2 loaded with 0.1wt.% Pt catalyst (0.1Pt/TiO2-A) was prepared via the impregnation method, and its CO catalytic oxidation activity was investigated. Noteworthy, introduction of H2O into the reaction atmosphere apparently facilitated the catalytic oxidation of CO. Besides, introduction of SO2 inhibited the catalytic oxidation of CO. In presence of H2O and SO2, 0.1Pt/TiO2-A showed outstanding catalytic stability, and X-ray photoelectron spectroscopy (XPS) and thermogravimetric (TG) characterizations suggested that the amount of sulfate species deposited on the 0.1Pt/TiO2-A treated at 230 degrees C did not increase with time extension, which might be an important reason for the high sulfur resistance of 0.1Pt/TiO2-A. XPS results also demonstrated that the dissociation of H2O led to considerably increase of hydroxyl groups over the catalyst surface. (H2O)-O-18 isotope-labeling experiments unambiguously showed that C16O18O was the main product accounting for 88.9%, revealing that the other oxygen atom in the product CO2 was mostly from H2O. Consequently, based on previous researches and our experimental results, the mechanism of H2O promoting CO oxidation on 0.1Pt/TiO2-A catalyst was proposed.