Catalytic combustion of chlorobenzene over core–shell Mn/TiO2 catalysts

Abstract

Core–shell Mn/TiO2 mixed oxide catalysts (Mn/Ti-cs) were prepared by incipient-wetness impregnation method, and tested in the catalytic combustion of chlorobenzene (CB) as a model of chlorinated aromatics. The obtained catalysts were characterized by XRD, TEM, XPS, BET, and H2-TPR. It was found that Mn/Ti-cs catalysts with different mass ratios of Mn/Ti were found to possess high activity for catalytic combustion of CB. Among these, Mn/Ti20-cs was the most active catalyst, for which the complete combustion temperature (T90) of CB was 296 °C, which was higher than the compared Mn/TiO2 nanoparticles with the same Mn/Ti mass ratio (Mn/Ti20-np). We found that the porous structure and special morphology are the main factors to increase the catalytic activity. Mn/Ti20-cs can provide more reaction and adsorption sites, surface active oxygen species than Mn/Ti20-np on the catalyst surface, which was beneficial to the diffusion and degradation of CB molecule and other intermediate products. By increasing the Mn/Ti mass ratio to 30%, T90 was raised to 400 °C. This is due to the decrease of Mn3+/Mn ratio and specific surface area. Conversion of CB over the MnTi20-cs catalyst was maintained at 90% or more for 900 min, indicating the excellent stability of this catalyst.