Elemental Mercury Oxidation over Fe–Ti–Mn Spinel: Performance, Mechanism, and Reaction Kinetics

Abstract

The design of a high-performance catalyst for Hg 0 oxidation and predicting the extent of Hg 0 oxidation are both extremely limited due to the uncertainties of the reaction mechanism and the reaction kinetics. In this work, Fe–Ti–Mn spinel was developed as a high-performance catalyst for Hg 0 oxidation, and the reaction mechanism and the reaction kinetics of Hg 0 oxidation over Fe–Ti–Mn spinel were studied. The reaction orders of Hg 0 oxidation over Fe–Ti–Mn spinel with respect to gaseous Hg 0 concentration and gaseous HCl concentration were approximately 1 and 0, respectively. Therefore, Hg 0 oxidation over Fe–Ti–Mn spinel mainly followed the Eley–Rideal mechanism (i.e., the reaction of gaseous Hg 0 with adsorbed HCl), and the rate of Hg 0 oxidation mainly depended on Cl • concentration on the surface. As H 2 O, SO 2, and NO not only inhibited Cl • formation on the surface but also interfered with the interface reaction between gaseous Hg 0 and Cl • on the surface, Hg 0 oxidation over Fe–Ti–Mn spinel was obviously inhibited in the presence of H 2 O, SO 2, and NO. Furthermore, the extent of Hg 0 oxidation over Fe–Ti–Mn spinel can be predicted according to the kinetic parameter k E-R, and the predicted result was consistent with the experimental result.