Novel Synergistic Effect of Fe and Mo in FeMoS/TiO for Recovering High Concentrations of Gaseous Hg from Smelting Flue Gas: Reaction Mechanism and Kinetics.

There is a high demand for developing a more effective and environment-friendly technology to substitute the complicated and hazardous Boliden-Norzink technology for recovering gaseous Hg from smelting flue gas. In this work, a low-cost and reproducible sorbent (FeMoS/TiO) was developed to recover gaseous Hg from smelting flue gas. FeMoS/TiO exhibited a superior ability for capturing high concentrations of Hg, with an adsorption rate of 72.2 μg g min and a capacity of 41.8 mg g at 60 °C. These were generally larger than the sums of those of FeS/TiO and MoS/TiO The kinetic model of Hg adsorption by FeS/TiO, MoS/TiO, and FeMoS/TiO were constructed according to the adsorption mechanism. Then, the structure-activity relationship of FeMoS/TiO for Hg capture was determined by comparing the kinetic parameters. The intrinsic adsorption of Hg by MoS/TiO (i.e., physically adsorbed Hg was oxidized by MoS to HgS) was inhibited marginally after FeS was incorporated. However, another Hg adsorption route (i.e., physically adsorbed Hg was oxidized by FeS to HgS) appeared on FeMoS/TiO. Its rate was significantly higher than that of FeS/TiO. Thus, a novel synergistic effect of Fe and Mo in FeMoS/TiO for Hg capture was observed.