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

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