Effect of WO3 and MoO3 doping on the interaction mechanism between arsenic oxide and V2O5-based SCR catalyst: A theoretical account

Abstract

WO3 and MoO3 are widely used as the additives for the V2O5-based selective catalytic reduction (SCR) catalysts, which have different anti-arsenic poisoning performances. To clarify their different influence mechanism on the interaction between arsenic oxide (As2O3) and the V2O5-based catalyst, WO3 and MoO3 doped V2O5/TiO2 catalyst models were built, density functional theory (DFT) method was employed to explore the interaction mechanism for As2O3 with V2O5, WO3 and MoO3 from a theoretical level. As2O3 adsorption configurations, adsorption energies and electronic structures were obtained, along with the detailed inter-reaction pathways and relevant energy barriers. The results indicate that strong interaction and electron transfer occur after As2O3 adsorption, the MoO3 doped catalyst has higher reactivity and stronger charge transfer with As2O3 than the WO3 doped catalyst. Moreover, on V2O5-WO3/TiO2 catalyst, the reactivity of WO3 with As2O3 is lower than that of V2O5, hence As2O3 is inclined to react with V2O5, resulting in the catalyst deactivation. Whereas for V2O5-MoO3/TiO2 catalyst, As2O3 tends to react with the more active MoO3, thus protecting the V2O5 from arsenic poisoning. In summary, MoO3 doping provides better anti-arsenic poisoning effect than WO3, which agrees well with previous experimental results.