CO
2-enhanced coalbed methane recovery (CO
2-ECBM) has been demonstrated as an effective enhanced oil recovery (EOR) technique that enhances the production of coalbed methane (CBM) while achieving the goal of CO
2 sequestration. In this paper, the grand canonical Monte Carlo simulation is used to investigate the dynamic mechanism of CO
2-ECBM in anthracite pores. First, an anthracite pore containing both organic and inorganic matter was constructed, and the adsorption and diffusion characteristics of CO
2 and CH
4 in the coal pores under different temperature and pressure conditions were studied by molecular dynamics (MD) simulations. The results indicate that the interaction energy of coal molecules with CO
2 and CH
4 is positively associated with pressure but negatively associated with temperature. At 307.15 K and 101.35 kPa, the interaction energies of coal adsorption of single-component CO
2 and CH
4 are −1273.92 kJ·mol
−1 and −761.53 kJ·mol
−1, respectively. The interaction energy between anthracite molecules and CO
2 is significantly higher compared to CH
4, indicating that coal has a greater adsorption capacity for CO
2 than for CH
4. Furthermore, the distribution characteristics of gas in the pores before and after injection indicate that CO
2 mainly adsorbs and displaces CH
4 by occupying adsorption sites. Under identical conditions, the diffusion coefficient of CH
4 surpasses that of CO
2. Additionally, the growth rate of the CH
4 diffusion coefficient as the temperature increases is higher than that of CO
2, which indicates that CO
2-ECBM is applicable to high-temperature coal seams. The presence of oxygen functional groups in anthracite molecules greatly influences the distribution of gas molecules within the pores of coal. The hydroxyl group significantly influences the adsorption of both CH
4 and CO
2, while the ether group has a propensity to impact CH
4 adsorption, and the carbonyl group is inclined to influence CO
2 adsorption. The research findings are expected to provide technical support for the effective promotion of CO
2-ECBM technology.
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