Influence of Sm on the low temperature NH3-SCR of NO activity and H2O/SO2 resistance over the SmaMnNi2Ti7Ox (a=0.1, 0.2, 0.3, 0.4) catalysts

A series of Sm-modified SmaMnNi2Ti7Ox (a = 0.1, 0.2, 0.3, 0.4) catalysts were synthesized and showed better NH3-SCR activity than MnNi2Ti2Ox, meanwhile, the Sm0.3MnNi2Ti7Ox sample exhibited much higher low temperature NH3-SCR performance below about 200 degrees C, and good SO(2 )and/or H2O durability. The bulk and surface physicochemical properties were measured to investigate the influence of the Sm addition on the activity by various characterization methods including NO/NH3 oxidation, NH3-TPD, H,-TPR, XRD, N-2 adsorption-desorption, XPS. The results illustrate that the Sm addition can not only increase the adsorbed NO/NH3 species, BET surface area, surface acid amount, Mn4+ content, surface adsorbed oxygen and the redox ability but also inhibit the generation of ammonium sulfate/bisulfate, which are beneficial to the NH3-SCR activity. Moreover, the in situ diffuse reflectance infrared Fourier transform spectroscopy was applied to analyze the reaction process, which reveals that the NH3-SCR reaction follows both E-R and L-H mechanisms over Sm0.3MnNi2Ti7Ox.