Enhanced low temperature NH3-SCR activity and SO2 tolerance by Cu-SSZ-13/R(Sm, Pr,Y or La)MnOx coupled catalysts

Abstract

A series of Cu-SSZ-13/R(Sm, Pr, Y or La)MnOx composite catalysts were successfully synthesized by self-assembly method. Among them, the low-temperature NH3-SCR activity and sulfur resistance of Cu-SSZ-13 is most effectively improved by coupling with SmMnOx. The abundant adsorbed Oads species in SmMn2O5 can promote the oxidation of NO to NO2 and triggers the "fast SCR" reaction, which is an important reason for the excellent low-temperature NH3-SCR activity of the composite catalyst. Moreover, the electron transfer between the SmMn₂O₅ and Cu-SSZ-13 interface facilitates the redox cycling of Mn³⁺/Mn⁴⁺ and Cu²⁺/Cu⁺, thus improving NO conversion and retaining a wide temperature window in NH3-SCR reaction. Meanwhile, the SmMnOx species can be used as sacrificial sulfur-trapping sites, which effectively prevented the sulfation of the copper active sites and thus significantly improve the SO2 tolerance of the composite catalysts. This work elucidates the synergistic reaction mechanism of Cu-SSZ-13/SmMnOx coupled catalysts and thereby provides theoretical guidance for the rational design and development of high-efficiency NH3-SCR catalysts.