Synthesis of three-dimensional ordered mesoporous MnOx/CeO2 bimetal oxides for the catalytic combustion of chlorobenzene

Abstract

A series of CeO₂ supported ordered mesoporous MnO_x/CeO₂ bimetal oxides with 3-D bi-continuous pore structure were prepared by an incipient-wetness impregnation method, and used in the catalytic combustion of chlorobenzene (CB) as a model of dioxins. The as-synthesized catalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H₂-TPR), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) N₂ adsorption, respectively. The effect of pore structure and Mn loading content on catalytic properties and textural structure had been explored. On Mn/Ce(0.43) (molar ratio Mn/Ce equal to 0.43), the T₉₀ (temperature at which 90% conversion is attained) is 279 °C. Compared with other MnO_x/CeO₂ samples with different Mn loading contents, the high activity of Mn/Ce(0.43) is ascribed to well dispersed MnO_x and a large amount of active chemisorbed oxygen species. This Mn/Ce(0.43) catalyst can maintain 90% CB conversion at 350 °C for at least 1000 min. And kinetics of on Mn/Ce(0.43) at 200 and 300 °C showed a dependence of rate on CB concentration is of first order, well within the inlet CB concentration from 500 to 2000 ppm. In addition, the T₉₀ of Mn/Ce(0.43) is significantly lower than that of the general Mn/Ce-NPs, and the enhanced activity of Mn/Ce(0.43) is due to its bi-continuous 3-D ordered pore structure.