LAUSR

Abstract This paper reports an investigation of using graphene oxide (GO) nanofluids to improve CH4 separation from low-concentration coalbed methane (LCCBM) via gas hydrate formation. The effect of GO nanofluids on LCCBM purification was evaluated by performing experiments at different concentrations of graphene oxide nanoparticles (GONs) and operation pressures. It was found that both the rates of hydrate formation and gas consumption were enhanced when graphene oxide nanoparticles were added to the liquid phase. Moreover, CH4 separation efficiency was greatly increased as compared to the systems without GONs. With the elevation of operation pressure, the hydrate formation kinetics was enhanced but the CH4 separation efficiency was reduced. The experimental conditions of 286.6 K, 2.0 MPa, and 500 ppm GONs were preferred for CH4 separation from LCCBM. The energy consumption for gas compression and system cooling at this temperature and pressure condition is lower than other LCCBM purification systems reported in the literature. The CH4 concentration in LCCBM was increased from 30 mol% to 76 mol% after two-stage hydrate-based separation. Therefore, the GO nanofluids have a great potential to improve the kinetics of hydrate formation as well as the purification efficiency of LCCBM.