Progress of research on purification of CH4 from a CH4/CO2/N2 mixture by pressure swing adsorption

The high methane (CH₄) content of landfill gas, biogas, and coal bed methane (CBM) makes them attractive substitutes for natural gas. Nevertheless, the calorific value of the energy produced by burning as well as the overall effectiveness of energy gas use are both reduced in the presence of impurity gases, such as CO₂ and N₂. Thus, achieving the effective separation of CH₄ from CO₂ and N₂ is crucial for increasing energy efficiency, reducing the greenhouse effect, and achieving the dual-carbon aim. This is also the key to enriching and concentrating this kind of gas energy and using it efficiently. With a focus on the development of carbon-based materials, zeolite molecular sieves, and metal–organic frameworks in the field of CO₂/CH₄/N₂ separation in recent years, this paper primarily addresses the types of adsorbents, molecular simulation, and process optimization involved in the purification of CH₄ by variable pressure adsorption. Finally, the development bottlenecks and application prospects of different adsorbents in CH₄ purification applications are foreseen in conjunction with basic research and process evaluation.