Study on the Mechanism of HS Adsorption by Different Functional Groups of the Coal Surface Based on Density Functional Theory, Gran Canonical Monte Carlo, and Molecular Dynamics.

In order to reveal the relationship between different functional groups and the adsorption performance of HS molecules at the molecular level and to investigate the influence mechanism of HS molecule adsorption characteristics, Materials Studio was used to study the adsorption characteristics of different functional groups: hydroxyl, carboxyl, carbonyl, ether bond, pyridine, pyrrole, thiophene, methyl, benzene, mercaptan, thioether, sulfone, and sulfoxide on HS gas based on the methods of grand canonical Monte Carlo (GCMC), molecular dynamics (MD), and density functional theory (DFT). Research has shown that the absolute values of adsorption energy, from high to low, are Ph-COOH > Ph-pyridine > Ph-pyrrole > Ph-OH > Ph-C-O-C > Ph-C═O > Ph > Ph-methyl > Ph-sulfoxide > Ph-mercaptan > Ph-sulfone > Ph-thioether > Ph-thiophene > HS-HS. The adsorption of HS by functional groups is the result of a combination of physical and microchemical adsorption. In the early stage of adsorption, functional groups attract HS gas molecules through electrostatic and van der Waals forces, causing HS molecules to approach the functional group. When approaching the hydrogen bonding range of 0.26-0.31 nm, electron transfer occurs between functional groups and HS molecules, and hydrogen bonding occurs between carboxyl, carbonyl, hydroxyl, pyridine, sulfone, and sulfoxide functional groups and HS molecules, resulting in microchemical interactions. The potential energy curves of functional groups and HS molecules conform to Lennard-Jones theory, and the order of saturated adsorption capacity and adsorption energy is consistent. HS molecules have obvious layering characteristics in narrow pores.