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

• K 2 O deactivated Ce-Ti oxide catalyst more seriously than KCl at the same K loading. • Fewer Ce3+ and chemical adsorbed oxygen on the surface of K 2 O-CT. • Lower surface acidity and worse reducibility over K 2 O-CT. • K species inhibited the adsorption of NH 3 and promoted the formation of NO x. Based on experiments and DFT studies, CeO 2 -TiO 2 catalyst was found to be deactivated by KCl or K 2 O, and the poisoning effect of K 2 O was more serious than that of KCl. The characterization results showed that compared with KCl, K 2 O 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 CeO 2 -TiO 2 catalyst. The results of in situ DRIFT showed that K 2 O had a stronger inhibition effect on NH 3 adsorption on the catalyst surface than KCl. The introduction of K 2 O or KCl promoted the adsorption of NO on the catalyst surface, but not all NO x adspecies were reactive in the NH 3 -SCR reaction. These results were further demonstrated by DFT calculations. The PDOS of different K species doped CeO 2 -TiO 2 catalysts and the adsorption energies of oxygen vacancy, chemisorption oxygen, NH 3 and NO x 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 NH 3 on the catalyst surface, all of which led to the decrease in the catalytic activity. [ABSTRACT FROM AUTHOR]