Simulation Study on Adsorption Characteristics of Mine Gases by Oxygen Functional Groups on Coal Surface

Based on the density functional theory simulation method, the adsorption behaviors of four typical mine gases (CO, CO₂, CH₄ and N₂) on the surface oxygen-containing functional groups of coal are simulated from the atomic level. The adsorption mechanism of four kinds of gases on coal surface functional groups is investigated. Four kinds of gases simulate the adsorption behavior of six common functional group structural units on the coal surface: phenolic hydroxyl group, carboxyl group, carbonyl group, ether bond, alcoholic hydroxyl group and alkyl group. The results show that the adsorption energy, adsorption configuration and frontier orbit are calculated and analyzed. The adsorption strength of coal and four gases exists: CO₂>N₂>CO>CH₄, and the order of adsorption of oxygen-containing functional groups on each coal surface model is: carboxyl group> alcoholic hydroxyl group> phenolic hydroxyl group> carbonyl group> Ether bond > alkyl group.