Insights into Samarium Doping Effects on Catalytic Activity and So2 Tolerance of Mnfeox Catalyst for Low-Temperature Nh3-Scr Reaction

The development of catalysts with high NH3 -SCR activity in the presence of SO2 was urgent for non-electric industries to control NOx emission at low temperature. Herein, a series of Sm-doping MnFeOx catalysts were synthesized through a typical PEG-assisted co-precipitation method and applied for low-temperature NH3 -SCR process. SmMnFe-0.1 catalyst significantly broadened the activation temperature window and yielded almost 100% NO conversion from 75 to 200 °C, moreover, the NO removal efficiency could still maintain at about 90% in the presence of SO2 and H2O. The characterization results confirmed that Sm could optimize the dispersity of active components and enlarge the surface area of catalyst. Furthermore, strong interaction among active ions facilitated more oxygen vacancies and accelerated NO oxidation to NO2 , further cooperating with abundant adsorbed NH3 , leading to cause “Fast SCR” reaction. Both catalysts were dominated by the E-R mechanism desipte MnFeOx catalyst also obeyed the L-H pathway. Particularly, the intense redox cycles between Sm and Mn inhibited the electron transferring from SO2 to Mn ions, and induced that Fe species serving as sacrificial sites along with Sm to preferentially react with SO2 , resulting in an enhanced SO2 tolerance, and the possible mechanism model was proposed