Deactivation Mechanism and Enhanced Durability of V2O5/TiO2–SiO2–MoO3 Catalysts for NH3−SCR in the Presence of SO2

Abstract V 2 O 5 /TiO 2 ‐type catalysts are widely applied for selective catalytic NO reduction by NH 3 (NH 3 ‐SCR), but enhanced sulfur tolerance and low‐temperature activity are required. Herein, V 2 O 5 /TiO 2 −SiO 2 −MoO 3 (V/TSM) was demonstrated to have excellent catalytic activity and durability for NH 3 ‐SCR in the presence of SO 2 at temperatures lower than 200 °C. The deactivation mechanism and factors influencing SO 2 durability were investigated using catalytic durability tests, Fourier‐transform infrared spectroscopy, and temperature‐programmed desorption/decomposition. Our results revealed that (NH 4 ) 2 S 2 O 3 and NH 4 HSO 4 form on catalyst surfaces by NH 3 −SO 2 −H 2 O reactions at low temperatures, resulting in catalyst deactivation via pore blockage. However, V/TSM was found to possess an increased number of active sites for decomposing deposited ammonium sulfate salts. The decomposition activity was related to the solid acidity, which enhanced SO 2 desorption and reactions between ammonium sulfate salts and NO. These findings will contribute to the development of catalysts with improved lifetimes for NH 3 −SCR.