Enhanced SO2 and H2O resistance of MnTiSnOy composite oxide for NH3-SCR through Sm modification

• Doped Sm activate surface adsorbed oxygen and increase the acid content. • The bidentate nitrates adsorbed on Sm 0.2 MnTiSnO y participate in the NH 3 -SCR reaction. • Sm 0.2 MnTiSnO y follows Langmuir-Hinshelwood (L-H) mechanism. NO x is one of the main sources of air pollution, and the abatement of NO x emission has aroused increasing attention. The NH 3 -SCR technology is mature and widely used for controlling NO x emissions from fixed sources. In this work, Sm x MnTiSnO y was synthesized by a mixed solvothermal synthesis. The NH 3 -SCR performance of Sm x MnTiSnO y was tested and the H 2 O and SO 2 resistance of Sm 0 MnTiSnO y , Sm 0.1 MnTiSnO y , and Sm 0.2 MnTiSnO y catalysts (5 %H 2 O, 25 ppm SO 2 ) were tested at 250 °C. The physicochemical properties of Sm x MnTiSnO y were studied by XRD, FESEM, TEM, BET, XPS, H 2 -TPR, NH 3 -TPD and In-situ DRIFTS. The experimental results reveal that Sm 0.2 MnTiSnO y has a better low-temperature NH 3 -SCR performance and splendid H 2 O and SO 2 durability. Moreover, appropriate Sm doping increases the specific area and enhances the acidity of the catalyst’s surface. The In-situ DRIFTS results suggest that the adsorption and activation of NH 3 are of primary importance in the NH 3 -SCR reaction. Besides, a large number of weak acid sites on Sm 0.2 MnTiSnO y are conducive to adsorb and activate NH 3 and good redox ability facilitates the activation of bidentate nitrate, respectively. Meanwhile, Sm doping could transfer electrons from the Sm species to the Mn species, which inhibits the formation of Mn sulfate.