Study on the ramifications of small molecule organic matter within the kinetic behavior of CH4 and CO2 adsorption

The complex pore structure and organic matter composition of coal significantly affect the storage and transportation characteristics of gas, and the role of soluble organic matter is still lacking in in-depth research. This study, represented by tetrahydrofuran-2-ol (C4H8O2), explores the effect of small molecule organic compounds on coal adsorption of CH4 and CO2 through quantum chemical simulations. The static potential of a single molecule was determined through quantum chemistry calculations. Detailed analysis was conducted on the adsorption heat, mean square displacement, radial distribution function, and adsorption energy distribution during the adsorption process. The results indicate that the excessive adsorption capacity of coal for CO2 is always higher than that for CH4. Organic small molecules significantly reduce the gas adsorption capacity and adsorption heat of coal, weaken the interaction between heteroatoms and adsorbate molecules, and have a significant impact on CO2 adsorption, thereby significantly reducing the interaction between CO2 and coal molecules and weakening the displacement effect of CO2 on methane. At 6 MPa, its impact on CO2 adsorption is minimal. The results of this study contribute to a better understanding of the occurrence mechanism of coalbed methane, providing theoretical support for optimizing pre extraction gas technology and assisting in coal mine safety and efficient production.