In situ DRIFTS and TPD studies on surface properties affecting SO2-resistance of Pt/TiO2 catalyst in low-temperature CO oxidation

Abstract

By pre-calcining two TiO2 (P25 and anatase) supports at various temperatures, Pt/TiO2 of different Pt valence states, surface hydroxyls (OH), and peroxide contents were prepared. Pt/Anatase 450 and Pt/P25 450, whose supports were pre-calcined at 450 °C, performed excellently in the CO oxidation catalytic activity test using flue gas without water and SO2. Their low T50 (165 and 175 °C, respectively) and high TOF at 125 °C (0.204 and 0.247 s−1, respectively) of CO oxidation are attributed to the low stability of the adsorbed CO on Pt sites. Furtherly, in the catalytic test using water and SO2-containing flue gas, the catalysts using anatase supports achieved higher performance than P25 supports, showing T50 of 182−186 °C and TOF of 0.202−0.207 s−1 at 165 °C. The in situ DRIFTS study and TPD analysis indicate that OH participates in the sulfate formation. The limited hydroxylation on the anatase surface provides a small amount of OH, thereby mitigating the stable sulfate accumulation. Less stable sulfate on anatase than P25 gives rise to the high activity of anatase-supported catalysts.