A DFT study of the Hg0 oxidation mechanism on the V2O5-TiO2 (001) surface

the mechanism of Hg-0 oxidation is of great significance in increasing Hg-0 removal efficiency over selective catalysis reduction (SCR) catalyst. In this study, DFT and periodic slab model are performed on a V2O5-TiO2 (001) surface to investigate the reaction mechanism for Hg-0 oxidation. On the same surface model, three kind of heterogeneous catalysis mechanisms proposed are systemically studied, namely Langmuir-Hinshelwood mechanism, Eley-Rideal mechanism and Mars-Maessen mechanism. By analyzing the relationship between energy barriers and oxidizing capacity of the lattice oxygen atoms in V2O5, it is concluded that Mars-Maessen mechanism is more reasonable. The importance of HCl is not only its dissociation is the rate-limiting step in the overall catalytic cycle, but also HCl dissociative adsorption promotes the formation of O- and V4+ or V3+ ion with oxidizing capacity. The gas phase O-2 is considered to be used in recovery the oxygen vacancies generated in catalyst regeneration. Our study provides atomic-scale insight into Hg-0 oxidation mechanism which is helpful to the catalyst modification. (C) 2017 Elsevier B. V. All rights reserved.