Effect of K poisoning on denitration performance of catalyst

Abstract The V2O5–WO3/TiO2 catalyst samples loaded with different forms of K salt(KCl, KNO3 and K2SO4)were prepared by an impregnation method. The results of catalytic activity evaluation tests illustrated that different forms of K salt poisoned the catalyst and decreased its denitrification efficiency. However, the degree of poisoning was different. The stronger the acid formed by acid ions, the stronger the counter acting effect on the poisoning of the catalyst. This is related to the acidity change of the Bronsted and the Lewis acid sites on the surface of the catalyst caused by different forms of K poisoning. The results also found that SO2 enhances the catalyst activity of different forms of K poisoning in flue gas, by reducing the degree of poisoning. The mechanism was that the acid SO2 enhanced the acidity of the Lewis acid sites on the catalyst surface. The results of SO2 conversion rate evaluation test indicated that different forms of K poisoning improve the conversion rate of SO2 to SO3. The strengthening effect of K2SO4 poisoning of the catalyst was the most significant, KNO3 was next, and KCl the least. This was related to the change of electronegativity and stability of the V–O–M oxygen bridge caused by different forms of K poisoning.