Denitrification performance and sulfur resistance mechanism of Sm-Mn catalyst for low temperature NH3-SCR

MnOx and Sm-Mn catalysts were prepared with the coprecipitation method, and they showed excellent activities and sulfur resistances for the selective catalytic reduction of NOx by NH3 between 50 and 300 degrees 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 SO2 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 SO2 and the amount of surface adsorbed oxygen. The Bronsted acid sites strengthen significantly due to the addition of SO2, enhancing the sulfur resistance of the 0.10Sm-Mn catalyst.

Automated summary

MnOx and Sm-Mn catalysts prepared by coprecipitation method demonstrated excellent activities and sulfur resistances in the selective catalytic reduction of NOx by NH3 at temperatures between 50 and 300 degrees C with excess oxygen. 0.10Sm-Mn catalyst showed superior catalytic activity and sulfur resistance. The addition of Sm affected the phases, morphology structures, gas adsorption, reaction process, and specific surface areas, resulting in enhanced NO conversion, N-2 selectivity, and sulfur resistance. Extensive investigations were conducted on the reaction mechanism and the impact of SO2 on the catalysts.