Mechanistic insight into the catalytic CO oxidation and SO2 resistance over Mo-decorated Pt/TiO2 catalyst: The essential role of Mo

The problem of CO oxidation in incomplete combustion from steel industry is that the deactivation of Pt-based catalysts by SO2. Here, we have elaborately designed a series of Mo-decorated 0.1 wt% Pt/TiO2 catalyst (Pt/Mo/Ti) catalyst. The catalytic test showed that the Pt/3Mo/Ti catalyst achieved 100 % CO conversion above 200 °C and maintained excellent long-term catalytic stability in the presence of SO2. The enhancement in SO2-tolerance ability was due to the suitable Brønsted acidity to weaken the SO2 adsorption and strong charge transfer ability to reduce the oxidation of SO2 to SO3. Aberration-corrected scanning transmission electron microscopy (STEM) suggests that the Pt-O-Mo species are present in atomically dispersed form in the Pt/3Mo/Ti catalyst. The surface O = MoO4 sites with terminal Mo = O bond prevented SO2 from reacting with platinum, thus inhibiting its migration to TiO2 and TiOSO4 formation. We also revealed the strong interaction between platinum and molybdenum and characterized the CO oxidation pathway in the presence of SO2. This research offers new insights into the mechanism of the catalytic CO oxidation and SO2 resistance over Mo-decorated Pt/TiO2 catalyst.