Shape and size effects on adsorption performance of methane from pores in coal

To investigate the impact of pore shape and size on methane adsorption characteristics in coal reservoirs. This study utilized the grand canonical Monte Carlo and molecular dynamics simulations to explore the variations in methane adsorption within different pore structures. The mechanisms by which different pore shapes affect methane adsorption phase density were analyzed, and the relative impact of various factors on methane adsorption was clarified. The research findings indicate that the methane average density within the pores decreases with increasing pore size. Square and triangle pores exhibit higher methane density peaks due to the greater adsorption potential from the angles formed by the pore walls under the same conditions. While pore size is small (<1.5 nm), the adsorption force fields within the pores overlap, and circle pores exhibit the largest methane adsorption amount. As pore size increases (>1.5 nm), triangle and inlay pores create strong adsorption potential regions due to the apex angles at their tips, resulting in a trend of maximum adsorption amounts. Comparing adsorbed methane proportion under different conditions shows that pore size has the greatest influence. In summary, identifying the mechanism of methane adsorption in different pore structures will aid in optimizing the evaluation of gas content.