Influence of components on methane micropore filling capacity of low-rank coal

N₂/CO₂ adsorption methods were used to measure pore characteristics of low-rank coal, and methane isothermal adsorption experiments were conducted for further evaluation. Results from N₂ adsorption experiments reveal that the pore size ranges from 1.03 to 3.26 nm, with pore volumes (PVs) of 0.006–0.013 cm³/g The CO₂ adsorption experiments reveal that the micropore size distribution is 0.479–0.548 nm, with PVs of 0.026–0.056 cm³/g. The methane isothermal adsorption experiments shows that the maximum adsorption volume is 12.82–28.68 cm³/g. The micropore filling theory developed for medium to high-rank coals shows that over 94.71 % of methane is stored in micropores, validating its applicability to low-rank coal. Through theoretical analysis and calculations, a dimensionless expression has been derived for the relationship between the micropore filling capacity of methane in low-rank coal and the content of its various components. This study offers a theoretical foundation for outburst prevention of gas in low-rank coal mining regions.