Novel synthesis of reed flower-like SmMnO catalyst with enhanced low-temperature activity and SO resistance for NH-SCR.

In this work, a novel co-precipitation coupled solvothermal procedure is proposed to prepare a SmMnO catalyst (SmMnOx-CP + ST) with a reed flower-like structure for the selective catalytic reduction of NO by NH (NH-SCR). Over 90% NO conversion and N selectivity was achieved at a low temperature range (25-200 °C), and 96% NO conversion was achieved in the presence of 100 ppm SO at 75 °C. While the NH-SCR of the SmMnO catalysts prepared by co-precipitation (SmMnO-CP) and solvothermal (SmMnO-ST) methods performed much poorer than the SmMnO-CP + ST catalyst. All catalysts were characterized by XRD, BET, SEM, XPS, H-TPR, NH-TPD, NO-TPD, and FT-IR. The results revealed that the superior performance of the SmMnO-CP + ST is due to the unique reed flower-like structure morphology, which endows the SmMnO-CP + ST with the largest surface area, the strongest synergistic reaction of Sm and Mn, abundant surface oxygen species and surface active sites, and significantly enhances the redox ability. Furthermore, the amorphous reed flower-like structure showed strong short-range ordered interaction between the active components and weaken the formation of sulfates species. In addition, the highest content of Mn and Mn+Mn greatly promotes the redox cycles of Sm↔Mn and Sm↔Mn, and suppresses the production of sulfate species in the presence of SO.