Promoting effect of Pd modification on the M/TiO2 (M = V, Ce, Mn) catalyst for catalytic oxidation of dichloromethane (DCM)

Abstract

To improve the catalytic oxidation of dichloromethane, a series of Pd modifying M4/TiO2(M = V, Ce, Mn) catalysts were prepared by impregnation method and characterized by ICP-MS, XRD, BET, O2/NH3-TPD, H2-TPR, XPS and DRIFT. It was found that Pd0.12V4/TiO2 catalyst possessed the best catalytic performance with excellent CO2 selectivity and stability compared to other catalysts. Characterization results illustrated that Pd modification improved the redox ability of catalyst to oxidize DCM to intermediates mainly CO, and the addition of Pd also slightly improved the surface adsorbed oxygen species, which played a great role in further oxidation of CO to CO2. Meanwhile, the V2O5 loading can maximize the acidity of catalyst, which is beneficial for the adsorption of DCM and cleavage of C-Cl bond. The reaction mechanism was concluded that DCM firstly adsorbed on surface acid sites to be further oxidized to CO which then was oxidized to CO2 by the surface adsorbed oxygen species.