Effect of Sulfur on Mn/Ti Catalysts Prepared Using Chemical Vapor Condensation (CVC) for Low-Temperature NO Reduction

Mn/Ti catalysts prepared through impregnation of manganese acetate and a manganese nitrate precursor via the chemical vapor condensation (CVC) method were investigated in this study to assess NH 3 -selective catalytic reduction (SCR) activity. Manganese (Mn) loaded on a synthesized TiO 2 catalyst showed good low-temperature NO reduction activity and better resistance to sulfur poisoning in presence of SO 2 . Mn loaded on synthesized TiO 2 prepared from manganese acetate precursor especially exhibited a high NO conversion of 98.4% at 150 °C. Moreover, it presented high NO conversions within the entire operating temperature window in comparison with other catalysts, which may be attributed to smaller particle size, scattered amorphous Mn over the catalyst surface, higher dispersion, and an abundant Mn 2 O 3 phase. X-ray photoelectron spectroscopy (XPS) analysis of the spent catalyst following the SCR reaction in presence of SO 2 verified that the formation of sulfated titanium and manganese sulfate was significantly inhibited, and that the deposition concentration of ammonium sulfate on active sites was low owing to impregnation of Mn acetate onto synthesized TiO 2 . FT-IR analysis indicated that the catalyst also contained larger quantities of N–H bonds in NH 3, synchronizing with Lewis acid sites on its surface.