Keywords: 
• V2O5-WO3/TiO2 /
• Zinc species /
• Poisoning /
• NOx /
• Dioxin

Abstract: The flue gas from iron ore sintering process is one of the largest sources of nitrogen oxide (NOx) and dioxins emission in industries. The V2O5-WO3/TiO2 (VWTi) catalyst can simultaneously remove NOx and dioxins, but the complex flue gas composition will cause the catalyst deactivation. In this study, ZnCl2, ZnO and ZnSO4 poisoning experiments on VWTi catalyst were carried out by the wet impregnation method. The effects of different zinc speacies on simultaneous removal of NOx and dioxin (chlorobenzene (CB) was used as the dioxins simulant) from VWTi catalyst were studied under simulated conditions of iron ore sintering flue gas. The surface physicochemical properties of the fresh and poisoned catalysts were characterized to reveal the deactivation mechanism. The results show that the loading of different Zn species had inactivation effect on the simultaneous removal of NOx and CB on the catalysts, and the poisoning effect was more obvious with the increase of Zn content. Zinc species caused a slight agglomeration of particles on the surface of catalysts, a decrease in the number of surface acid sites, a reduction in the reducibility of surface vanadium species, and a decrease in the surface chemisorption oxygen ratio and the molar ratio of n(V5+)/n(V4+). The introduction of SO42- could create some new acid sites for adsorption and conversion of HN3 and CB. The results of regeneration experiments confirm that dilute sulfuric acid solution washing was an effective method for recovering the catalytic activity, but the water washing failed to restore the activity. Finally, a possible poisoning mechanism of the VWTi catalysts in the flue gas from iron ore sintering process was proposed.