Unravelling the promotional effect of Nb and Mo on VOx-based catalysts for NOx reduction with NH3

Abstract

A series of VxNbMoTi for the selective catalytic reduction (SCR) of NO by NH3 have been synthesized to improve the SCR performance at low temperatures and the SO2 durability of vanadium-based catalysts. In this study, Nb and Mo were selected as promoters for vanadium-based catalysts in the SCR reaction, and the introduction of an appropriate amount of Nb-Mo enhanced the activity and SO2 durability at low temperatures. With the addition of Nb and/or Mo, physicochemical analysis was performed to characterize of the catalysts. The introduction of Nb-Mo into VTi increased the total amount of NH3 adsorption and improved the Vn+ (n = 3, 4) fraction. In addition, the number of oxygen vacancies and the amount of labile oxygen increased. Thus, introducing Nb-Mo into VTi increased SCR performance and enhanced resistance to SO2 and H2O in the presence of SO2 and H2O by reducing the affinity between SO2 and the catalytic surface.