Comparative Study of Tetra-N-Butyl Ammonium Bromide and Cyclopentane on the Methane Hydrate Formation and Dissociation

Abstract

Two widely investigated methane hydrate promoters, tetra-n-butyl ammonium bromide (TBAB) and cyclopentane (CP), for methane hydrate formation and dissociation were comparatively investigated in the quiescent reactor at 2.5 °C and 8 MPa. The results indicated that the increase in the mass fraction TBAB decreased the induction time. However, it did not significantly affect the methane uptake. In the presence of CP, the increase in the CP concentration resulted in an increase in the induction time due to the increasing thicknesses of the CP layer in the unstirred reactor. Moreover, the methane uptake was varied proportionally with the CP concentration. The addition of TBAB resulted in a higher methane uptake than that of CP, since the presence of TBAB provided the cavities in the hydrate structure to accommodate the methane gas during the hydrate formation better than that of CP. On the contrary, the presence of CP significantly increased the induction time. Although the methane recovery remained relatively the same regardless of TBAB and CP concentrations, the recovery was higher in the presence of TBAB.

Studies on Methane Gas Hydrate Formation Kinetics Enhanced by Isopentane and Sodium Dodecyl Sulfate Promoters for Seawater Desalination

“…The linear trend of gas consumption for M6 (Figure 5b) represents the growth hydrate stage. Similar findings were also derived in a study by Chanakro et al (2020) [46]. However, the gas intake of the seawater/IP system was initially much lower than that of the M1, M3, M5, M7, and M8 systems.…”

Microscopic Insights into the Effect of the Initial Gas–Liquid Interface on Hydrate Formation by In-Situ Raman in the System of Coalbed Methane and Tetrahydrofuran

“… 26 Besides, tetra- n -butylphosphonium bromide (TBPB) was also adopted to capture the methane from mine ventilation air with extremely low methane content, whereby the methane could be enriched by around 3.5-fold via the hydrate process. 31 Moreover, a high dose of quaternary ammonium salt needs to be added to form a massive hydrate for enhancing the cage occupancy of methane molecules and reducing the induction time of hydrate formation 32 because the cations of tetra- n -butylammonium (TBA + ) or phosphonium (TBP + ) involve in forming a part of the cage-lattice of the hydrate cavities. 33 THF as a famous hydrate promoter was firstly introduced to capture methane from CBM by Zhang et al 24 The methane content could be increased in the range of 38.06–41.76 mol % from 26.00 mol % by adding a THF concentration of 1.0 mol %.…”