One-pot synthesis of monolithic Mn-Ce-Zr ternary mixed oxides catalyst for the catalytic combustion of chlorobenzene

摘要

Mn-based catalysts have been widely investigated for the disposal of chlorinated volatile organic compounds (CVOCs), due to their excellent catalytic performances. In this study, Ce-Zr co-modified monolithic Mn-based oxide catalysts were synthesized by one-pot solution combustion method. All the samples were tested with chlorobenzene (CB), as a model molecule of CVOCs. The Mn-Ce-Zr catalyst retained high surface area, small particle size and high redox properties, and exhibited superior catalytic activity with T-90% at 390 degrees C. The superior catalytic activity of Mn-Ce-Zr catalyst originated from the larger specific surface area, the higher Mn4+ cation and surface oxygen contents, as well as the greater oxygen mobility and manganese reducibility. The catalytic activity declined slightly during the life test and the reduced activity could be partially regenerated by introducing water vapor. H-2-TPR results indicated that the blockage of active sites by strongly adsorbed chlorine species contributed to the deactivation. By-products generated during CB oxidation included phenol, 2-butene, 2-butenal, acetone, trichloromethane, etc., no highly toxic polychlorinated aromatic compounds were detected. CB oxidation was initiated by CeCl bond cleavage followed with ring-open reactions. This work developed a monolithic Mn-Ce-Zr ternary mixed oxides catalyst with striking activity and stability and provided some insightful understandings for designing industrial catalysts.