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

Abstract

NOx is one of the main sources of air pollution, and the abatement of NOx emission has aroused increasing attention. The NH3-SCR technology is mature and widely used for controlling NOx emissions from fixed sources. In this work, SmxMnTiSnOy was synthesized by a mixed solvothermal synthesis. The NH3-SCR performance of SmxMnTiSnOy was tested and the H2O and SO2 resistance of Sm0MnTiSnOy, Sm0.1MnTiSnOy, and Sm0.2MnTiSnOy catalysts (5 %H2O, 25 ppm SO2) were tested at 250 °C. The physicochemical properties of SmxMnTiSnOy were studied by XRD, FESEM, TEM, BET, XPS, H2-TPR, NH3-TPD and In-situ DRIFTS. The experimental results reveal that Sm0.2MnTiSnOy has a better low-temperature NH3-SCR performance and splendid H2O and SO2 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 NH3 are of primary importance in the NH3-SCR reaction. Besides, a large number of weak acid sites on Sm0.2MnTiSnOy are conducive to adsorb and activate NH3 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.