Abstract: The direct emission of low-concentration coal bed methane not only causes energy waste,but also brings serious environmentalharm such as greenhouse effect.The purification of low concentration coalbed methane by PSA is an effective way to solve the emission of coalbed methane.In this paper,the research on separation of methane from CH_4/N_2 system in coalbed methane using the technology ofpressure swing adsorption was summarized,including separation mechanism and the corresponding pressure swing adsorption purificationtechnology;the advantages and disadvantages of two kinds of technology were analyzed,and the research progress and existing problems ofCH_4/N_2 adsorption separation effect on porous adsorption materials were discussed such as activated carbon,carbon molecular sieve,zeo-lite molecular sieve and metal organic skeleton materials.Pressure swing adsorption technology based on equilibrium effect separation hasencountered a bottleneck in the practical application of CH_4/N_2 system separation since the equilibrium separation coefficient of existingadsorbents is too small and the concentration enhancement is limited.Secondly,CH4 is preferentially adsorbed as a strong adsorption com-ponent in the equilibrium effect. The product gas must be obtained by vacuum desorption,and multistage compression and additional dis-placement steps must be taken,so the energy consumption is relatively high. The enriched product gas with pressure can be directly ob-tained at the top of the towerbased on the separation of dynamic effect,meanwhile,the energy consumption of multi-stage compression isavoided,and it has a significant advantage comparing with the equilibrium effect separation. However,since the first stage is required to bepressurized,there are some safety risks in the treatment of coal-bed methane near the explosion limit concentration.Activated carbon is atypical equilibrium separation adsorbent with large adsorption capacity,strong processing capacity,and low price,but the separation coeffi-cient is low,and activated carbonhas the disadvantages of large gas circulation volume,low efficiency,and narrow concentration range. Howto improve the equilibrium separation coefficient of activated carbon through pore size control and surface modification will be the focus offuture research.Currently,carbon molecular sieves have been reported to be the main kinetic adsorbents with good results. However,due totheir high price and limited industrial promotion,it will be an important direction for pressure swing adsorption to separate CH_4/N_2 in thefuture by selecting appropriate and cheap raw materials,changing the current intermittent production process,and further developing effi-cient and cheap kinetic selective adsorbents.Zeolites preferentially adsorb methane,in contrast to kinetic effects which preferentially adsorbnitrogen,which reduce the separation selectivity of CH_4/N_2.Therefore,Si-Al zeolites/Ti-Si zeolites mostly perform well in the separationof natural gas and oilfield gas with high concentration of CH_4,while it is rarely applied in the purification of CH_4 with low concentration ofCBM,and there is no industrial application report.The emergence of metal-organic framework materials provides a new development idea,but there arethe few research on CH_4/N_2 adsorption balance and kinetics as well as pressure swing adsorption separation,which need to befurther studied. Therefore,the solution of stable forming and amplification of materials is still a technical bottleneck to be broken through.The author believes that the future pressure swing adsorption purification process will be a combination of equilibrium effect and kineticeffect,and the development of separation process under low pressure will have better economy and safety.The development of low cost,high capacity and high selectivity adsorbent is still the key development direction of adsorbent in the future. The adsorbent life and regener-ation performance need to be further studied.