Effects of Pore Structure on Methane Adsorption and Diffusion Properties in Varying-Rank Coals Modified by Tetrahydrofuran

, and the initial methane diffusion velocity presents a linear positive correlation with the Langmuir volume constant. THF reduces methane adsorption sites and improves pore connectivity through a dual mechanism of "dissolution and pore expansion" and "surface modification", which promotes the desorption and seepage of adsorbed methane. The relevant results provide theoretical support and technical insights for the efficient extraction of CBM in low-permeability and high-gas coal seams.