Nanosized Zn-In Spinel-Type Sorbents for Elemental Mercury Removal from Flue Gas

摘要

A series of novel Zn-In spinel-type sorbents were synthesized and were for the first time used to remove elemental mercury from flue gas. Zn-In spinel-type sorbents exhibited excellent mercury removal performance, and ZnIn2S4 sorbent showed Hg-0 removal efficiency of 96.2% at 125 degrees C. The effects of flue gas components were examined, and it was found that the presence of SO2 and H2O has little effect on Hg-0 capture. ZnIn2S4 has an excellent SO2- and H2O-resistance for Hg-0 capture. O-2 can promote Hg-0 adsorption over the ZnIn2S4 sorbent. The adsorption capacity of the synthesized ZnIn2S4 sorbent is as high as 1526 mu g.g(-1). Temperature-programmed decomposition desorption and X-ray photoelectron spectroscopy analyses demonstrate that the adsorbed mercury can be transformed into HgS with the sulfur sites of the surface, and the adsorption of elemental mercury on ZnIn2S4 sorbent occurs by chemisorption. Density functional theory calculations were carried out to reveal the interactions between the Hg-0 atom and the ZnIn2S4 (110) surface. The results show that the mercury transformation reaction pathway over ZnIn2S4 sorbent occurs through two steps: Hg-0. HgS(ads). HgS. The theoretical calculations support the experimental observation that it is difficult for the captured Hg to be released from the sorbent surface. Considering the excellent Hg-0 removal performance and SO2 and H2O-resistance, Zn-In spinel sorbents can serve as a promising material for mercury removal.