Catalytic oxidation of dimethyl sulfide with ozone: Effects of promoter and physico-chemical properties of metal oxide catalysts Original Research Article

This study reports improved catalytic activities and stabilities for the oxidation of dimethyl sulfide (DMS), a major pollutant of pulp and paper mills. Ozone was used as an oxidant and activities of Cu, Mo, Cr and Mn oxides, and mixed metal oxides supported on γ-alumina, were tested over the temperature ranging from 100 to 200 °C. The best catalytic activity was obtained over 10 wt.% CuO-10 wt.% MoO3 supported on γ-Al2O3 with 100% DMS conversion and high selectivity (≈96%) towards complete oxidation products such as CO2 and SO2. The addition of molybdenum to the CuO/γ-Al2O3 significantly enhanced the selectivity of the reaction towards complete oxidization products indicating that MoO3 acts as a good promoter when used with CuO. Catalyst characterization by XRD, TPR and NH3-TPD analyses suggested that these promoting effects are due to the formation of Cu3Mo2O9 and CuMoO4 species on CuO-MoO3/γ-Al2O3, and also a substantially higher quantity of acid sites and a stronger acid strength in CuO-MoO3/γ-Al2O3 than CuO/γ-Al2O3 catalyst. This study also reports the optimization of reaction parameters and effects the catalyst physico-chemical properties have on the catalytic activity.