Performance enhancement of elemental mercury removal from syngas over Fe7SC sorbent: Experimental and theoretical studies

In this study, a Fe7SC sorbent was prepared via hydrothermal impregnation and used to eliminate Hg-0 from simulated syngas. A certain amount of oxygen was introduced to induce targeted H2S oxidation to form active surface sulfur species for the enhanced capture of Hg-0 over Fe7SC. The effects of the introduced oxygen, temperature, and syngas composition (H2S, CO, H-2, and H2O) on Hg-0 adsorption performance were investigated. Xray photoelectron spectroscopy, Hg-0-temperature programmed desorption, and density functional theory calculations were performed to elucidate the Hg-0 removal mechanism. Fe7SC exhibited a superior Hg-0 removal performance (approximately 99.2%) in the presence of H2S + O-2 at 150 degrees C. The interaction between H2S and the introduced oxygen was responsible for its superior Hg-0 capture capacity. CO and H-2 suppressed Hg-0 adsorption, and H2O inhibited Hg-0 removal owing to competitive adsorption. Results of the Bangham kinetic analysis indicate that Hg-0 surface chemisorption is the primary rate-controlling step. Hg-0 adsorption on the Fe7SC sorbent may follow the Eley-Rideal mechanism, in which the active sulfur species generated from H2S oxidation react with gaseous Hg-0 to form HgS.

Automated summary

In this study, a Fe7SC sorbent was prepared via hydrothermal impregnation for the removal of Hg-0 from simulated syngas. The introduction of oxygen enhanced the capture of Hg-0 by inducing targeted H2S oxidation. The effects of oxygen, temperature, and syngas composition on Hg-0 adsorption performance were investigated. Fe7SC exhibited superior Hg-0 removal performance in the presence of H2S + O2. The interaction between H2S and oxygen was responsible for its enhanced Hg-0 capture capacity. CO and H2 suppressed Hg-0 adsorption, while H2O inhibited Hg-0 removal due to competitive adsorption. The kinetic analysis suggested that Hg-0 surface chemisorption was the rate-controlling step.