Investigation of Methane Adsorption and Diffusion Behavior in Hydrogen Sulfide-Containing Coal Seams

This study aimed to investigate the methane adsorption-diffusion problem in coal seams containing hydrogen sulfide. Molecular simulations and Materials Studio software were used to study the difference in behavior between hydrogen sulfide and methane adsorption, as well as the effect of hydrogen sulfide on methane adsorption-diffusion behavior in coal seams. Comprehensive data were obtained on the influence of hydrogen sulfide on methane's adsorption amount, probability density distribution, interaction energy, and diffusion coefficient during the adsorption. The results showed that as the hydrogen sulfide content increased from 0 to 1.9%, porosity decreased from 14.41% to 11.25%, representing a 21.93% reduction. When methane and hydrogen sulfide were adsorbed in the coal seam, the adsorption amount of hydrogen sulfide was notably higher, with an adsorption heat of 38.25 kJ/mol, which is 24.65 kJ/mol greater than that for methane. An increase in the hydrogen sulfide content caused several adverse effects, including a decrease in methane's adsorption amount, Langmuir adsorption constant, and number of available adsorption sites within bituminous coal. Furthermore, the interaction energy and diffusion coefficient of methane molecules diminished during adsorption.