Polymerization State of Vanadyl Species Affects the Catalytic Activity and Arsenic Resistance of the V2O5-WO3/TiO2 Catalyst in Multipollutant Control of NOx and Chlorinated Aromatics

The conventional V2O5-WO3/TiO2 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 NH3 selective catalytic reduction (NH3-SCR), but their promotion mechanism remains in debate and has yet to be explored in multipollutant control (MPC) of NOx 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 V2O5-WO3/TiO2 catalyst, while Mo doping resulted in vanadyl polymerization with an enriched V5+ chemical state and exhibited superior MPC activity and COx selectivity. Our work shows that antipoisoning catalysts can be designed with the combination of site protection and occurrence state modification of the active species.

Automated summary

The conventional V2O5-WO3/TiO2 catalyst is significantly poisoned by arsenic, resulting in a loss of catalytic activity. The doping of Al or Mo has been found to promote the arsenic resistance in NH3 selective catalytic reduction (NH3-SCR), but the mechanism behind this promotion is still debated. Our experimental and theoretical studies reveal that arsenic species preferentially adsorb on Al or Mo, forming arsenates and avoiding bonding with the active V sites. Furthermore, Al doping reduces the mobility of near-surface and bulk lattice oxygen, while Mo doping enhances MPC activity and COx selectivity through vanadyl polymerization and an enriched V5+ state.