Effect of different potassium species on the deactivation of V2O5-WO3/TiO2 SCR catalyst: Comparison of K2SO4, KCl and K2O.

The effect of different potassium species, including K 2 O, KCl and K 2 SO 4 , on the deactivation of V 2 O 5 -WO 3 /TiO 2 catalysts were measured in the research. Potassium species were supplied by impregnating catalyst with corresponding KNO 3 , KCl and K 2 SO 4 aqueous solution. Catalytic activity was also measured and the physical and chemical properties of fresh and poisoned catalysts were characterized by XRD, N 2 physisorption, NH 3 -TPD, H 2 -TPR, XPS and NH 3 -DRIFTS. Deactivation could be observed in the potassium-containing catalysts and the deactivation rate follows KCl > K 2 O > K 2 SO 4 . The surface chemisorbed oxygen was also reduced and the downward trend was in good accordance with the SCR activity. In addition, both the amount and stability of the Brønsted and Lewis acid sites dropped after potassium introduction, and the reducibility of surface active species decreased. The introduction of SO 4 2− created new Brønsted acid sites and performed advantages to ammonia adsorption and NO reduction. Cl − could react with vanadia active sites to form -O-V-Cl bond, which provided some new ammonia adsorption sites, but these newly generated sites could not revitalize the adsorbed ammonia and were helpless to catalytic activity promotion. Besides, KCl presented the maximum impact on catalyst reducibility was another contribution to its largest activity decline. Finally, the probable poisoning mechanisms of different potassium species over V 2 O 5 -WO 3 /TiO 2 catalysts were proposed. [ABSTRACT FROM AUTHOR]