Hydrate-Based Gas Separation for Methane Recovery from Coal Mine Gas using Tetrahydrofuran

Coal mine methane (CMM) gas is an unconventional natural gas that can be used as a clean supplementary energy resource when the methane is enriched. In this work, a new technology for separating methane from low-concentration CMM gas was investigated using gas hydrate formation in the presence of tetrahydrofuran (THF). The concentration of THF was fixed at 19 %, the initial pressure fixed at 0.3 MPa, 0.5 MPa, 0.8 MPa, 1.0 MPa, respectively, and the temperature was maintained at 278.15 K. The results indicated that gas hydrate formation and the separation of CH4 can be easily achieved at 0.3-1.0 MPa in THF solution. It was determined that the hydrate-based separation process for CH4 recovery from the CMM gas mixture performed better at medium and low initial pressures. The separation factor decreased from 9.5451 to 7.1834 as the reaction pressure rose from 0.3 to 1.0 MPa.