Evaluation of separation effect for CH₄ enrichment from coalbed methane (CBM) under the synergistic action of temperature and pressure based on IAST theory

Abstract

The synergistic pressure and temperature swing adsorption (SPTSA) technology is designed for purifying coalbed methane (CBM) are proposed in this work. Cyclic processes including four steps: cooling, pressurization, heating, and depressurization. Ideal adsorption solution theory (IAST) was used to evaluate the separation effect. Super activated carbons (SACs) with specific surface area exceeds 3000 m2 g−1 were prepared and used as adsorbents. From 273 to 373 K, the adsorption selectivity (S) changes more than 4, while the S changes less than 2 with the pressure changes from 0.1 to 9 MPa, indicating that temperature change is more conducive to improve the CH4 purity compared to the pressure change. However, more CH4 purification capacity can be obtained by pressure change. In cyclic SPTSA process, the CH4 purification capacity is generally increased by more than 30% compared with the pressure swing adsorption technology, which indicated that CH4 separation and purification under the synergistic action of temperature and pressure is theoretically feasible and has a broad prospect in the CBM purification. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd.