KCl-induced deactivation of V2O5–WO3/TiO2 catalyst during selective catalytic reduction of NO by NH3: Comparison of poisoning methods

Abstract Deactivation of V2O5/TiO2 catalysts during selective catalytic reduction (SCR) of NO by NH3, especially the alkali metal-induced deactivation, has received much attention in recent years. Many researches have been done using different poisoning methods to understand the deactivation behavior of catalyst in industry, but the results were somewhat inconsistent. This work compares the poisoning methods – wet impregnation, solid diffusion and vapor deposition from the viewpoint of deactivation rate and deactivation mechanism using V2O5–WO3/TiO2 as the catalyst and KCl as the poisoning substance. Results indicate that deactivation extent of the catalyst depends not only on the quantity of KCl but also on how KCl is introduced to the catalyst, following an order of vapor deposition ≫ solid diffusion > wet impregnation. The presence of V2O3 species due to interaction of K with oxygen in vanadium oxides is mainly responsible for the catalyst deactivation by wet impregnation. The formation of K2S2O7–V2O5 eutectic is mainly responsible for the catalyst deactivation by solid diffusion at a higher K/V ratio and vapor deposition due to the significant decrease of NH3 adsorption and increase in NH3 oxidation activity.