Effect of Absorbed Sulfate Poisoning on the Performance of Catalytic Oxidation of VOCs over MnO2

Manganese oxides have displayed vast potential for future development in the field of catalytic abatement of volatile organic compounds (VOCs) because of their low cost, high stability, and enhanced catalytic activity. Manganese sulfate and manganese chloride are widely used as reaction sources to prepare manganese oxides. As reported, absorbed chloride usually affects the performance of catalysts. However, the effect of absorbed sulfate on catalysts has been overlooked at present. Herein, the poisoning effect of absorbed sulfate on MnO2 catalyst in the catalytic oxidation of VOCs has been uncovered. Manganese sulfate-derived MnO2 catalyst exhibits a significantly enhanced performance after repeated washing by water, which indicates that absorbed sulfate has an adverse effect on MnO2 catalyst for removal of VOCs. The blocking of the surface oxygen species and active sites is considered as the reason for sulfate poisoning. Hence, elimination of absorbed sulfate by thorough washing or other effective method is essential for preparing high-performance manganese sulfate-derived manganese oxide catalysts.