Hg Conversion over Sulfureted HPMo/γ-FeO with HCl at Low Temperatures: Mechanism, Kinetics, and Application in Hg Removal from Coal-Fired Flue Gas.

Recently, sulfureted metal oxides have been developed for the catalytic oxidation of Hg to HgCl using HCl as an oxidant at low temperatures, and they exhibit excellent Hg removal performance. Owing to the lack of reaction mechanisms and kinetics, further improvement in their performance for Hg conversion is extremely restricted. In this study, the reaction mechanism of Hg conversion over sulfureted HPMo/γ-FeO with HCl at low temperatures was investigated using Hg balance analysis and transient reaction. The chemical adsorption of Hg as HgS and the catalytic oxidation of Hg to HgCl both contributed to Hg conversion over sulfureted HPMo/γ-FeO. Meanwhile, the formed HgCl can adsorb onto sulfureted HPMo/γ-FeO. Then, the kinetics of Hg conversion, Hg adsorption, and HgCl desorption were developed, and the kinetic parameters were gained by fitting the Hg balance curves. Subsequently, the inhibition mechanism of HO and SO on Hg conversion over sulfureted HPMo/γ-FeO was determined by comparing the kinetic parameters. The kinetic model suggested that both HgCl resulting from Hg oxidation and unoxidized Hg can be completely adsorbed on sulfureted HPMo/γ-FeO with a moderate mass hourly space velocity. Therefore, sulfureted HPMo/γ-FeO can be developed as a reproducible sorbent for recovering Hg emitted from coal-fired power plants.