Denitrification performance and sulfur resistance mechanism of Sm-Mn catalyst for low temperature NH 3 -SCR

MnO x and Sm-Mn catalysts were prepared with the coprecipitation method, and they showed excellent activities and sulfur resistances for the selective catalytic reduction of NO x by NH 3 between 50 and 300 °C in the presence of excess oxygen. 0.10Sm-Mn catalyst indicated better catalytic activity and sulfur resistance. Additionally, the Sm doping led to multi-aspect impacts on the phases, morphology structures, gas adsorption, reactions process, and specific surface areas. Therefore, it significantly enhances the NO conversion, N 2 selectivity, and sulfur resistance. Based on various experimental characterization results, the reaction mechanism of catalysts and the effect of SO 2 on the reaction process about the catalysts were extensively explored. For 0.10Sm-Mn catalyst, manganese sulfate and sulfur ammonium cannot be generated broadly under the influence of SO 2 and the amount of surface adsorbed oxygen. The Bronsted acid sites strengthen significantly due to the addition of SO 2 , enhancing the sulfur resistance of the 0.10Sm-Mn catalyst.