The enhanced Pb resistance of CeO2/TiO2 catalyst for selective catalytic reduction of NO with NH3 by the modification with W

Abstract

• The modification of CeO2/TiO2 catalyst with W could neutralize its deactivation by PbO. • The amount of brønsted acid sites increased significantly ascribed to increased surface Ce3+and the highly dispersed W species. • The oxidation of NO to NO2 was motivated after w doping. • The PbO resistance mechanism of W was proposed. The novel CeO 2 /TiO 2 catalysts were modified by W in this work. It revealed that W modification could significantly facilitate the capacity of CeO 2 /TiO 2 catalyst for resisting Pb poisoning. And various characterizations were applied to explore the underlying resistance mechanism. XPS and H 2 -TPR analysis revealed that the W modification promoted the transformation from surface Ce 4+ to Ce 3+ . Then the increased surface Ce 3+ along with highly dispersed W species provided more Brønsted acid sites for NH 3 adsorption on the surface of CeO 2 /TiO 2 catalyst (NH 3 -TPD and DFT). By XPS and NO+O 2 co-adsorption results, the oxidation of NO to NO 2 was motivated due to the increased surface chemisorbed oxygen. Furthermore, both E-R and L-H mechanisms were suitable for the NH 3 -SCR reaction over CWT and CT catalysts according to in situ DRIFT analysis. The deposition of PbO merely inhibited the NH 3 and NO x adsorption, while the NH 3 -SCR mechanism wasn't changed.