Phase equilibria of semi-clathrate hydrates of tetra-n-butyl phosphonium bromide at atmospheric pressure and in presence of CH 4 and CO 2  + CH 4

Phase Equilibria for Gas Hydrates Formed with Methane or Ethane + Tetra-n-Butylphosphonium Bromide + Water

“…This work is related to the study of the influence of TBPB on the formation of methane or ethane semiclathrate hydrates toward the development of natural gas storage. The three-phase, L–H–V, equilibria for the CH 4 + TBPB + H 2 O system have been reported elsewhere. ,, Suginaka et al reported measurements of methane hydrates in the presence of TBPB at w TBPB = 0.35, in the temperature and pressure ranges of 282.7–291.5 K and 0.15–5.10 MPa, respectively. They reported eight equilibrium points and found that TBPB caused the phase equilibrium curve to shift to a stable region of pure CH 4 hydrates characterized by lower pressure and higher temperature.…”

“…They reported eight equilibrium points and found that TBPB caused the phase equilibrium curve to shift to a stable region of pure CH 4 hydrates characterized by lower pressure and higher temperature. Sales Silva et al reported dissociation temperatures of this system for seven aqueous TBPB solutions, w TBPB = 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, and 0.35. Measurements were made in the temperature range of 280.8–293.1 K and in the pressure range of 1–8 MPa, reporting 27 equilibrium points.…”

“…Surfactants, − salts, ,, and ionic liquids ,,− have been investigated as chemical agents to promote or to inhibit the gas hydrate formation. For gas storage/transportation applications, an additive that moves the three-phase equilibria to temperature conditions close to room temperature and moderate pressures is required.…”

“…Hydrogen semiclathrate hydrates were obtained with tetra- n -butylammonium bromide (TBAB), tetra- n -butylammonium chloride (TBAC), and tetra- n -butylphosphonium bromide (TBPB); , for CO 2 semiclathrate hydrates, TBAB, , TBAC, ,, tetra- n -butylammonium fluoride (TBAF), , tetra- n -butylammonium nitrate (TBANO 3 ), tetra- n -butylphosphonium chloride (TBPC), and TBPB ,,,, have been studied, having significantly higher hydrate dissociation temperatures than those of pure CO 2 hydrate . Formation of nitrogen semiclathrate hydrates has been explored using TBAB, , TBAC, TBAF, TBPC, and TBPB; ,, formation of methane semiclathrate has been carried out using TBAB, TBAF, TBAC, TBPC, and TBPB. ,, In general, the above-mentioned ionic liquids behave as thermodynamic promoters.…”

“…TBPB has shown promising properties for gas storage or gas separation applications. ,, TBPB semiclathrate hydrates have not been studied much to characterize the phase diagrams of gas + TBPB + water systems and test models for semiclathrate hydrates, which are significant to the development, design, and optimization of gas hydrate processes; thus, it is of great relevance to perform measurements on phase equilibrium conditions for gas + TBPB + water semiclathrate hydrates, especially at different TBPB compositions . This work is related to the study of the influence of TBPB on the formation of methane or ethane semiclathrate hydrates toward the development of natural gas storage.…”