Abstract: CO_2 sequestration enhancing coalbed methane recovery( CO_2_ECBM) is one of the important ways of CO_2 utilization.The underground storage and utilization of CO_2 can be realized,and recovery rate of coalbed methane can be improved by CO_2-ECBM.Affected by the complexity of coal seam geological conditions,CO_2 can't be completely sealed in coal seam after injection,and will gradually seep out with CBM drainage.The displacement of coal-bed methane containing CO_2 needs to be separated and removed before it could be transported to the pipeline network.Aiming at the production,composition and pressure conditions of displacement CBM,the adsorption characteristics of CO_2 and CH_4 on carbon molecular sieves were measured,and the equilibrium separation coefficients of CO_2/CH_4 were calculated.The separation and purification experiments of CO_2/CH_4 were carried out by pressure swing adsorption evaluation device,and the amount of adsorbent treated and the recovery of CH_4 were calculated.The results show that the adsorption of CO_2 and CH_4 on carbon molecule conforms to type I adsorption isotherm.The adsorption capacity of CO_2 is 1.27 mol/kg,the adsorption capacity of CH_4 is 0.48 mol/kg.The equilibrium separation coefficient of CO_2/CH_4 is 3.38,and the separation ratio of carbon molecular sieves is high,which is mainly based on the kinetic rate.CO_2 is got as adsorptive phase,CH_4 is got as non-adsorptive phase.With the condition of adsorption pressure of 600 k Pa,and adsorption time of 120 s,the concentration of CO_2 in the CO_2/CH_4 separation product gas was below 1% after pressure swing adsorption separation.With the condition of adsorption pressure of 500 k Pa,and adsorption time of 120 s,the concentration of CO_2 in the CO_2/CH_4 separation tail gas separation product gas was below 5% after pressure swing adsorption separation.The final product gas would be got with the mixing of the CO_2/CH_4 separated gas and the purified gas from the separation tail gas. CO_2/CH_4 is separated and purified by pressure swing adsorption,and the concentration of CO_2 in the product gas is below 1%.Taking 1 200 Nm~3/d of single well production as an example,treatment capacity of adsorbent per unit is about 100 Nm~3/h,and the recovery rate of CH_4 reaches 92.375%. The displaced CBM can be separated and purified by pressure swing adsorption to remove CO_2,and then transported to the pipeline network.