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 (R 2 = 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.