Review on separation of coalbed methane by hydrate method

Coalbed methane (CBM) is a kind of high-quality clean energy, which is mainly composed of adsorbed or free methane in coal seam. The separation and utilization of methane from CBM can effectively improve energy efficiency and reduce greenhouse effect. Gas hydrates are clathrate crystalline compounds composed of water and small molecular gases such as CH4, CO2, H2 and so on. Gas hydrate technology is an effective method to separate methane from CBM. This paper reviews the research progress in the separation of CBM by hydrate. The thermodynamic and kinetic studies are summarized, and the separation effects of different promoting systems are compared. By analyzing the hydrate-based separation of other gases, it is found that the CBM separation method combining hydrate technology with other separation technologies is expected to be a promising separation technology. Further work is needed to close the gap between gas separation science and industrial application. Therefore, the future research direction is proposed in this work, which has reference significance for the future research on separation of CBM efficiently.