Nitrogen oxide（NOx） emitted from stationary and mobile sources is a major air pollutant. Selective catalytic reduction（SCR） of NOx over a catalyst is a main technology for NOx elimination. Catalysts used for practical applications would be deactivated in flue containing SO2. In this work, three typical commercial catalysts were investigated before and after SO2 treatment. The catalysts were characterized by X-ray diffraction（XRD）, X-ray fluorescene（XRF）, temperature programme reduction（TPR）, temperature programme desorption（TPD） and diffuse reflectance Fourier transform infrared（DRIFT） techniques. Results showed that SO2 treatment significantly influenced the performance of V2O5/TiO2 catalyst. The amount of V2O5 in the catalyst primarily affected the accumulation of sulfur species in the SO2 atmosphere. The performance of catalysts with small amounts of V2O5 could be improved under the same experimental conditions for acidity enhancement.
A titania pillared interlayered clay（Ti-PILC） supported vanadia catalyst（V2O5/TiO2-PILC） was prepared by wet impregnation for the selective catalytic reduction（SCR） of NO with ammonia. Compared to the traditional V2O5/TiO2 and V2O5-MoO3/TiO2 catalysts, the V2O5/TiO2-PILC catalyst exhibited a higher activity and better SO2 and H2O resistance in the NH3-SCR reaction. Characterization using TPD, in situ DRIFT and XPS showed that surface sulfate and/or sulfite species and ionic SO4^（2-）species were formed on the catalyst in the presence of SO2. The ionic SO4^（2-） species on the catalyst surface was one reason for deactivation of the catalyst in SCR. The formation of the ionic SO4^（2-） species was correlated with the amount of surface adsorbed oxygen species. Less adsorbed oxygen species gave less ionic SO4^（2-） species on the catalyst.
