Adsorption Hydrate Hybrid Process for Methane Separation from a CH4/N2/O2 Gas Mixture Using Pulverized Coal Particles

In the present work, an adsorptionhydrate hybrid process was employed to enhance the separation of CH4 from a 30 mol % CH4/60 mol % N-2/O-2 gas mixture in the presence of pulverized coal particles. The incipient hydrate equilibrium conditions for gas hydrates formed from this CH4/N-2/O-2 gas mixture were measured in the presence of 1.0 mol % tetrahydrofuran (THF) and reported. Then, the characteristics of CH4 separation efficiency, gas uptake, and rate of gas consumption were studied at different saturations of the coal particles in the presence of 1.0 mol % THF. The experiments were carried out in batch operation with the initial pressure fixed at 3.6 MPa. The temperature was fixed at 277.1 K. The results indicated that hydrate formation is induced immediately by gas adsorption in the coal particles. Unsaturated coal particles perform better than saturated coal particles for CH4 separation from the CH4/N-2/O-2 gas mixture during the adsorptionhydrate hybrid process. The gas uptake and rate of gas consumption increased greatly as the saturation of the coal particles was reduced from 100% to 40%. In addition, the gas uptake obtained in the presence of pulverized coal particles was significantly increased as compared to those obtained in stirred reactors containing TBAB and CP/SDS. The CH4 recovery obtained at 277.1 K, 3.6 MPa, and 40% saturation of coal particles was about 33.5%, which was higher than those obtained in the presence of TBAB (26.2%) and CP/SDS (33.1%).