The poisoning effect of KCl and K2O on CeO2-TiO2 catalyst for selective catalytic reduction of NO with NH3

Based on experiments and DFT studies, CeO2-TiO2 catalyst was found to be deactivated by KCl or K2O, and the poisoning effect of K2O was more serious than that of KCl. The characterization results showed that compared with KCl, K2O could lead to a greater decrease in surface acidity, reducibility, the ratio of Ce3+/Ce4+ and the concentration of the chemisorbed oxygen on the surface of CeO2-TiO2 catalyst. The results of in situ DRIFT showed that K2O had a stronger inhibition effect on NH3 adsorption on the catalyst surface than KCl. The introduction of K2O or KCl promoted the adsorption of NO on the catalyst surface, but not all NOx adspecies were reactive in the NH3-SCR reaction. These results were further demonstrated by DFT calculations. The PDOS of different K species doped CeO2-TiO2 catalysts and the adsorption energies of oxygen vacancy, chemisorption oxygen, NH3 and NOx were calculated by MS DMol3. It was found that the introduction of K species weakened the reactivity of the catalyst surface, inhibited the formation of oxygen vacancies and chemisorption oxygen, and reduced the adsorption of NH3 on the catalyst surface, all of which led to the decrease in the catalytic activity.