Low-Coordinated Polysulfide Species on Metal Sulfide Enabled Superior Gaseous Mercury Removal from Natural Gas

The pursuit of efficient natural gas utilization is inherently linked to thorough purification of its contaminants. Traditional purification techniques, while adept at removing sulfur-containing acid gases (e.g., H₂S) and hydrocarbons, have overlooked a critical aspect: the efficient management of mercury, leading to storage tank corrosion and significant safety hazards in gas utilization. In this study, we demonstrate that core-shell ZnS@S_x enriched with low-coordinated polysulfide species, prepared by coating the sulfur shell through the in situ conversion of H₂S with additional SO₂ on the surface of the ZnS core, exhibits a superior saturated Hg⁰ adsorption capacity of 79.8 mg/g, over 1000 times that of the pristine ZnS counterpart. In situ spectroscopic analysis revealed a direct positive correlation (R² = 0.9524) between the concentration of short-chain S_x (x = 3-5) and Hg⁰ adsorption ability. Theoretical calculations further substantiated the superior adsorption energy of ZnS@S₄ for Hg⁰ among the various S_x species. Notably, the activity of ZnS@S_x is efficiently restored through intermittent online H₂S conversion, achieving the concurrent purification of mercury and partial acid gas, paving the way for a safer and more sustainable natural gas utilization.