Effect of Support Modification over VOx/TiO2 Catalysts for Enhancing Mercury Oxidation Activity through First-principles Calculations

Abstract

Catalytically and economically, oxidizing elemental mercury (Hg0) proves to be an efficient method for removing harmful mercury present in the flue gas from coal combustion facilities. Therefore, it is crucial to develop a highly active V2O5/TiO2 catalyst capable of oxidizing mercury. Support modification can alter the reactivity of V2O5/TiO2 by influencing the active center of V2O5, a factor critical to surface-reactant interactions. Thus, understanding the effects of support tuning methods, such as crystallographic phase control and reduction treatment, on mercury oxidation activity is valuable. In this study, density functional theory calculations were employed to mechanistically investigate how support tuning methods affect Hg oxidation reactivity and to elucidate changes in the electronic environment at the active site. Phase control on the TiO2 support was found to enhance Hg oxidation activity, whereas reduction treatment decreased activity due to changes in the charge density at V2O5. Furthermore, the reactivity change was explained using a Sabatier- like principle, highlighting the critical contribution of the interaction between the V site and surface Cl in balancing the competition between two key reaction steps: HCl dissociation and HgCl2 desorption. These findings offer guidance for enhancing the activity of VOx/TiO2 catalysts for various reactions, including Hg oxidation and selective catalytic reduction of