Characterisation of competitive adsorption of CH and CO mixed components in a coal body based on molecular simulation.

The competitive adsorption behaviour of CH and CO in coalbed methane mining is crucial for the optimisation of CO enhanced coalbed methane recovery (CO-ECBM) technology. In this paper, the giant canonical monte carlo (GCMC) method is used to simulate and study the competitive adsorption behaviour of CH and CO mixed component gases at different temperatures, pressures, water contents and molar ratios. The results showed that: the competitive adsorption capacity of CO was significantly stronger than that of CH, and the increase of its molar ratios could effectively replace CH; The increase of temperature or water contents decreased the heat of adsorption of equivalence of CH and CO as well as the Langmuir parameters a and b, which weakened the adsorption selectivity of CO, but the competitive ad-sorption advantage was still maintained; the competitive adsorption ad-vantages of CH were also maintained. However, its competitive adsorption advantage was still maintained; under the conditions of low pressure and high CO molar ratios, CO had the strongest ability to drive CH; under the conditions of high pressure and low CO molar ratios, the adsorption selec-tivity coefficient of CO to CH decreased the most; there was an upper limit of saturation in the driving of CH by CO, and even if the molar ratios con-tinued to increase, the driving efficiency was still low. There is a sat-uration limit for the substitution of CH by CO, and even if the molar ratios of CO continues to increase, the substitution efficiency is not significantly improved. This study reveals the competitive adsorption mechanism between CH and CO at the mo-lecular level, and provides a theoretical basis for optimising CO-ECBM technology and improving CBM recovery.