Effects of temperature and pressure on the methane hydrate formation with the presence of tetrahydrofuran (THF) as a promoter in an unstirred tank reactor

In this work, the effects of temperature and pressure on the methane hydrate formation and dissociation with the presence of 5.56 mol% THF solution in the quiescent condition is investigated. The experiments were conducted at 8 MPa and at 277.2, 283.2, 288.2 and 293.2 K. The results show that the methane uptake increased with the increase in the experimental temperature due to at the fact that higher experimental temperature showed the multiple hydrate nucleation and effective heat distribution to the surrounding. The experiment at 277.2 K showed the fastest induction time and shortest time to reach 90% of the methane uptake (t(90)). The highest methane uptake was observed at 293.2 K. Moreover, the effects of experimental over pressure on the methane hydrate formation was investigated by varying the pressure from 8 to 4 MPa at 288.2 K. The result showed that the pressure did not affect the methane uptake but the rate of formation at the higher pressure is higher than at lower pressure. Furthermore, this work reports the synergistic effects of kinetic promotion of methane hydrate formation by coupling THF with methyl ester sulfonate (MES) at 293.2 K. The results showed that the presence of MES increases both induction time and rate of hydrate formation. The dissociation experiment was conducted after the formation by increasing the temperature to 308.2 K. The results showed that up to 98% of methane could be recovered.