V2O5 supported on NbTiOx: A novel NH3-SCR catalyst with high performance induced by V-Nb-Ti interaction

Abstract

The traditional vanadia-based catalysts frequently employed for selective catalytic reduction of NOx with NH3 (NH3-SCR) have been criticized for their restricted operating temperature window and subpar low-temperature activity. In the present work, a series of NbTiOx solid solutions were used as supports to prepare V/NbxTi1-x (1.0 wt% V2O5) catalysts. The novel 1V/Nb0.15Ti0.85 catalyst presented superior catalytic performance and excellent resistance to SO2 in the SCR reaction, reaching above 95% NOx conversion in a wide temperature range from 270 to 485 °C. In comparison to pure TiO2, Nb-Ti-O solid solution support exhibited different pore structures and pore sizes, contributing to much larger specific surface area. Meanwhile, the surface Nb-OH and Nb = O bonds could serve as new acid sites to facilitate more NH3 adsorption. More importantly, there was a strong redox-acid interaction (V-Nb-Ti) for 1V/Nb0.15Ti0.85 catalyst, which induced the formation of highly redox-active V sites and promoted the activation of adsorbed ammonia, facilitating the NH3-SCR reaction. Unlike 1V/Ti, NOx species adsorbed on 1V/Nb0.15Ti0.85 participated in NH3-SCR reaction below 250 °C, further promoting the low-temperature activity. This study provides a novel vanadium-based catalyst with a low vanadium loading and high SCR activity for practical NOx abatement.