Interaction between support and V2O5 in the selective catalytic reduction of NO by NH3

Abstract

V2O5-based catalysts for NH3-selective catalytic reduction (SCR) have been prepared by an impregnation method using different supports including nano-TiO2, meso-TiO2, nano-ZrO2, meso-Al2O3 and meso-SiO2. Activity evaluations clarified that V2O5/meso-TiO2 possessed the highest activity and a wide activity–temperature window of 240–400 °C, while V2O5/nano-TiO2 and V2O5/nano-ZrO2 had activities were the next most active to V2O5/meso-TiO2. The realized NO removal was lowest over V2O5/meso-Al2O3 and V2O5/meso-SiO2. In flue gas with 900 ppm SO2 and 10 vol.% steam the catalyst V2O5/meso-TiO2 showed the best activity stability at 350 °C and 240 °C. Characterizing the catalysts revealed that the differences in their redox properties and acidities should be responsible for their different activities and poisoning resistance. The dispersion of V2O5 on all the supports obviously decreased its H2-reduction temperature, and the lower the reduction temperature, the better the catalyst appeared to be in activity and poisoning resistance. Overall, only the TiO2 support and its consequent interactions with V2O5 guaranteed the expected good activity and also poisoning resistance for NH3-SCR of NO. The higher pore volume of meso-TiO2 enabled a larger tolerance capacity to ammonium sulfate and sulfite so that this catalyst had better low-temperature activity stability.