Characterization of microscopic adsorption of CH ₄ /O ₂ on lignite based on molecular dynamics

To reveal the factors that influence the competitive adsorption of CH 4 /O 2 gases in lignite, the adsorption characteristics and thermodynamic properties of lignite on single components of CH 4 and O 2 and different proportions of the mixed components at different temperatures and pressures were simulated using the gas-phase molecular-based cluster (GCMC) model. The result shows that: a) In the context of single-component adsorption, the quantity of gas adsorbed increases in proportion to pressure and decreases in proportion to temperature. Concurrently, the isosteric heat of adsorption exhibits a tendency to first decrease and then increase, in conjunction with pressure. b) In the context of the adsorption of a binary mixture of CH 4 /O 2 at a ratio of 5:5 by lignite, it was observed that the amount of CH 4 adsorbed exceeds the amount of O 2 adsorbed at low pressure, and conversely at high pressure. c) The adsorption selectivity coefficients of CH 4 on O 2 demonstrated a decreasing trend with increasing pressure; under all three ratios, CH 4 arrived first to reach the dominant adsorption site.