Polymerization State of Vanadyl Species Affects the Catalytic Activity and Arsenic Resistance of the VO-WO/TiO Catalyst in Multipollutant Control of NO and Chlorinated Aromatics.

The conventional VO-WO/TiO catalyst suffers severely from arsenic poisoning, leading to a significant loss of catalytic activity. The doping of Al or Mo plays an important role in promoting the arsenic resistance on NH selective catalytic reduction (NH-SCR), but their promotion mechanism remains in debate and has yet to be explored in multipollutant control (MPC) of NO and chlorinated organics. Herein, our experimental characterizations and density functional theory (DFT) calculations confirmed that arsenic species preferentially adsorb on both Al and Mo to form arsenate, thereby avoiding bonding to the catalytically active V sites. More importantly, Al doping partially converted the polymeric vanadyl species into monomeric ones, thereby inhibiting the near-surface and bulk lattice oxygen mobility of the VO-WO/TiO catalyst, while Mo doping resulted in vanadyl polymerization with an enriched V chemical state and exhibited superior MPC activity and CO selectivity. Our work shows that antipoisoning catalysts can be designed with the combination of site protection and occurrence state modification of the active species.