Abstract
V2O5-WO3/TiO2 catalyst was poisoned by impregnation with NH4Cl, KOH and KCl solution, respectively. The catalysts were characterized by X-ray diffraction (XRD), inductively coupled plasma (ICP), N2 physisorption, Raman, UV-vis, NH3 adsorption, temperature-programmed reduction of hydrogen (H2-TPR), temperature-programmed oxidation of ammonia (NH3-TPO) and selective catalytic reduction of NOx with ammonia (NH3-SCR). The deactivation effects of poisoning agents follow the sequence of KCl>KOH≫NH4Cl. The addition of ammonia chloride enlarges the pore size of the titania support, and promotes the formation of highly dispersed V = O vanadyl which improves the oxidation of ammonia and the high-temperature SCR activity. K+ ions are suggested to interact with vanadium and tungsten species chemically, resulting in a poor redox property of catalyst. More importantly, potassium can reduce the Bronsted acidity of catalysts and decrease the stability of Bronsted acid sites significantly. The more severe deactivation of the KCl-treated catalyst can be mainly ascribed to the higher amount of potassium resided on catalyst.
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