Effects of H2O and SO2 on the Performance of V2O5/TiO2 catalysts for selective catalytic reduction of NO in flue gas

V2O5/TiO2 catalysts were prepared by an impregnation method. Effects of H2O and SO2 on the performance of the catalysts were investigated in the selective catalytic reduction of NO with NH3. The results show that H2O exhibits an inhibiting effect on the selective catalytic reduction (SCR), but it reduces the formation of N2O. SO2 has no large impact on the activity of NO reduction over the catalysts in dry or wet simulated flue gas (ψ(H2O)=10%). The presence of H2O increases the amount of the Brønsted acid sites on the catalysts' surface, thereby increasing the amount of adsorbed NH3. The deNOx activity decreases with the increase of the volume fraction of H2O in flue gas. The reason is that a large amount of H2O depressed the reaction of NO with NH4+ adsorbed on Brønsted acid sites. SO2 is transformed to SO42- over the catalysts' surface. SO42- can enhance the acidity of the catalysts' surface, thereby increasing the speed of SCR reaction. © 2013 Chinese Society for Electrical Engineering.