Construction of mesoporous amorphous Smα-MnTiOx with high deNOx performance and sulfur Tolerance: Insight into the synergistic Sulfur-Resistant effect between Manganese-Samarium species

Abstract

Low-temperature SCR denitrification technology requires catalysts with both NO_x oxidation and NH₃ adsorption capabilities. However, most catalysts, such as MnO_x and MnO₂/TiO₂, with the problems of narrow activity temperature windows and low sulfur resistance. Herein, the mesoporous amorphous oxide catalysts Sm_α-MnTiO_x are successfully synthesized by a solvothermal method. The catalyst displays excellent low-temperature activity and sulfur tolerance, with a denitrification conversion of over 90 % within the range of 160°C to 350°C. Furthermore, the denitrification conversion wasis maintained at more than 98 % for 8 h at 250°C and 50 ppm SO₂ atmosphere. The reducibility capacity and surface acidity of Sm_α-MnTiO_x catalysts are improve by the doping of Sm, thus facilitating the adsorption and activation of NH₃ and O₂, which is beneficial for the improvement of catalytic activity. The in-situ DRIFTS shows the abundant chemisorbed oxygen on the surface of Sm_α-MnTiO_x favors NO₂ generation, and the doping of Sm extended the temperature range of NO₂ (50–250 ℃),which promotes the reaction towards the Fast-SCR reaction pathway at low temperatures. The combined effect of E-R mechanism and Fast-SCR reaction successfully broaden the denitration temperature window of Sm_α-MnTiO_x catalysts. Furthermore, the interaction between Mn and Sm species effectively inhibits the electron transfer from Mn to SO₂, which reduces the generation of metal sulfate and protects the active sites of the catalyst. This study provides new ideas for the improvement of denitrification catalysts with sulfur tolerance, water resistance and upper and lower catalytic activity.