Catalytic oxidation of chlorinated volatile organic compounds over Mn-Ti composite oxides catalysts: Elucidating the influence of surface acidity

[Display omitted] •MnxTi1-xOy shows different acidity and reducibility by adjusting Mn/Ti ratio.•Mn-O-Ti solid solution accounts for more Lewis acidic sites on catalyst surface.•Surface acidity determines catalytic activity for VC oxidation when Mn/Ti > 0.4.•Mn0.4Ti0.6Ox with more acid sites and certain reducibility has a high activity.•The mechanism of Lewis acid participating in the VC oxidation is proposed. A series of Mn-Ti composite oxides (MnyTi1−yOx) were prepared via the sol-gel method, and their reducibility and surface acidity were controlled by adjusting the Mn/Ti molar ratio. In addition, as a model reaction, the catalytic activity of Mn-Ti composite oxides for the deep oxidation of vinyl chloride (VC) was evaluated. It was found that the catalyst surface acidity played a decisive role in the oxidation of VC, on the condition that the catalyst reducibility was superior to that of Mn0.4Ti0.6Ox. Consequently, a linear relationship between the surface acidity of the MnyTi1−yOx catalysts (y≥0.4) and the reaction rate of the VC oxidation process was observed. Moreover, the influence of Lewis acidic sites originating from Ti species on the catalytic activity of the MnyTi1−yOx catalysts was revealed. These results could lead to an efficient strategy for enhancing the CVOC oxidation reaction through finely tuning reducibility and surface acidity of the catalyst.