The effect of organic matter fraction extracted on micropores development degree and CH4 adsorption capacity of coal

The percentage of micropores in the pore structure of coal plays a significant role in methane (CH4) adsorption, whereas the fraction of organic matter in coal has a positive effect on CH4 adsorption. Ultrasonic waves were used to excite mixtures of organic solvents and coals with different degrees of deterioration. This process fa-cilitates the induction of surface organic matter in coal and the shedding of non-closed-ring side chains in the main structure of coal and the opening of closed rings. The samples extracted by organic solvents were subjected to electron microscopy detection, elemental analysis, and functional group analysis. The porosity of the samples showed distinct changes, and the sample with the best organic solvent extraction effect showed a sharp decrease in organic main carbon and a change in the distribution of partial functional group peaks. Through the exper-imental results of CH4, N2, and CO2 adsorption, the physical adsorption theory and density flooding theory with micropore filling theory were combined. It was found that the CH4 adsorption decreased, macro-and mesopore channels developed, and the percentage of micropores decreased. Overall, the filling effect caused by micro-chemistry had a significant influence on the macroscopic physical adsorption. Our research results provide theoretical guidance and a reference for the efficient exploitation of coalbed methane and mine gas control.