Mechanism of heterogeneous reaction between gaseous elemental mercury and H2O2 on Fe3O4 (110) surface

The Fe3O4 catalytic oxidation of gaseous elemental mercury (Hg-0) has been regarded as a promising method to control mercury from flue gases given its high efficiency, magnetic separation, and recyclable properties. Density functional theory (OFT) calculations were performed to study the heterogeneous reaction mechanism between Hg-0 and H2O2 over Fe3O4 (1 1 0) surface. The generation mechanism of surface hydroxyl on two Fe3O4 (1 1 0) layers was investigated. Binding energies, geometric parameters, and the Mulliken charge population of the possible configurations for Hg-0 interaction were studied. Results provided evidences that the H2O2 prefers to break the O-O bond and produces two OH groups, which combine with Hg-0 on Fe3O4 (1 1 0) A layer. The calculated binding energies suggested that the process of OH-H-OH and Hg-OH generation are exothermic on Fe3O4 (1 1 0) surface with H2O2. The Mulliken charge population revealed Hg-0 oxidation when systems were in equilibrium because a large number of electrons transfer from Hg-0 to the surface hydroxyl. The reaction of Hg oxidation followed the processes of Hg + OH -> Hg-OH, Hg-OH + OH -> HO-Hg-OH, and OH-Hg-OH desorption from the Fe3O4 (1 1 0) surface. (C) 2017 Elsevier B.V. All rights reserved.