Vanadium-density-dependent reactivity for simultaneous removal of NOx and Hg0 over V2O5/TiO2 catalyst

Abstract

Vanadium-based catalysts have been widely used in the simultaneous removal of NOx and Hg0. However, how vanadium species affect the reactivity of Hg0 oxidation and coverage-dependent behaviors of vanadium species are still unknown. Herein, we synthesized a series of V2O5/TiO2 catalysts with different V loadings and investigated the reaction characteristics of vanadium species (i.e., sub-monolayer, monolayer, and crystalline) for the catalytically simultaneous abatement of NOx and Hg0. At low V loading, the ratio of Oads/Olatt decreased gradually due to the VOx species occupying the defect sites of TiO2. The reaction rate of Hg0 oxidation is proportional to the square of the VOx density up to monolayer coverage. A maximum amount of V5+ is achieved at monolayer coverage and the TOF shows a volcanic trend with the increase of V loading. This study is an in-depth attempt to explore the effects of different vanadium species on the simultaneous removal of NOx and Hg0, and it is expected to provide theoretical guidance for the effective design of state-of-the-art vanadium-based catalysts for multipollutant control.