Poisoning effect of CaO on CeO2/TiO2 catalysts for selective catalytic reduction of NO with NH3

The effect of CaO on CeO2/TiO2 catalysts prepared by a single step sol-gel method for selective catalytic reduction of NO with NH3 was investigated. The results showed that CaO could severely deactivate the CeO2/TiO2 catalysts. Based on the characterization results obtained by BET, XRD, XPS, H-2-TPR and NH3-TPD, the deactivation by CaO of CeO2/TiO2 catalysts should be attributed to pore blockage, lower concentration of Ce on catalyst surface, reduction of Ce3+ and surface adsorbed oxygen, degradation of redox ability and decrease in NH3 adsorption capacity. The theoretical DFT results demonstrated that Ca atom could strongly interact with cerium oxygen, which inhibits the formation and hydrogenation of oxygen vacancies on catalyst surface.