Effect of co-existing SO2 on the catalytic activity of Sn supported alumina catalyst was investigated for the reduction of NO in the presence of high concentrations of oxygen and water vapor. Although the catalytic activity decreased at the initial stage of the activity test in the presence of SO2 over Al2O3, Sn/Al2O3 and Co/Al2O3, a stable NO conversion was observed afterwards. The steady state catalytic activity was in the order of Sn/Al2O3 > Co/Al2O3 > Al2O3. The catalytic activity of Sn/Al2O3 for NOx reduction in the low temperature region was increased with increasing Sn loading. 5 wt%Sn/Al2O3 showed the highest activity among Sn supported alumina catalysts. The accumulation of sulfur was observed on the spent catalyst, and its amount was closely related to the co-existing SO2 concentration and NOx conversion level. XPS and IR spectra measurements suggested the formation of Al2 (SO4) 3-like species on the catalyst surface. The efficiency of the reducing agent was in the following order methanol > ethanol > propylene > propane. In particular, methanol reduced NO most effectively on Sn/Al2O3.
