The different effect of SO2 on Zn-poisoned commercial V2O5-WO3/TiO2 catalysts with varied Zn loading

Commercial V 2 O 5 -WO 3 /TiO 2 (VWTi) catalysts used in NH 3 -SCR reaction with varied Zn loading were prepared and then effect of SO 2 on Zn-poisoned VWTi catalysts was investigated. Zn could cause the deactivation of VWTi catalysts. Nevertheless, the effect of SO 2 on Zn-poisoned VWTi catalysts varied with Zn loading. For Zn-poisoned catalyst with low content of Zn (1.0 wt.%, ZnL), SO 2 would promote the activity recovery of the catalyst. However, SO 2 had no influence on the Zn-poisoned catalyst with high Zn content (4.0 wt.%, ZnH). The catalyst was characterized by N 2 adsorption-desorption, XRD, XPS, SO 2 -TPD, NH 3 -TPD, H 2 -TPR and in situ DRIFTS. Tri-coordinated sulfate species were formed on ZnL sample in the presence of SO 2 , and the sulfate species could form new Brønsted acid sites, causing the recovery of activity. But ZnSO 4 was appeared and no Brønsted acid sites formed on ZnH sample under SO 2 , thus the activity of ZnH sample changed little.