Hydrate phase equilibria for CO2, CH4, or N2 + tetrabutylphosphonium bromide (TBPB) aqueous solution

The phase behavior of tetrabutylphosphonium bromide (TBPB) semi-clathrates with three gases, viz. CO2, CH4 or N2 was investigated in this study. The measurements were performed using a static high pressure cell using the isochoric pressure search technique. In order to determine the thermodynamic stability conditions of the semi-clathrates, the equilibrium data were measured at various concentrations of TBPB, viz. (0.05, 0.075, 0.10, 0.15, and 0.20) mass fraction TBPB. Measurements were undertaken in the temperature range of (279.3–291.4) K and in the pressure range of (1.06–7.79) MPa. The results indicate that TBPB has a promotion effect on semi-clathrate hydrate formation for the pure gas systems under consideration. •Hydrate phase behavior of TBPB with CO2, CH4 or N2 is investigated.•The measurements were performed using a static high pressure cell using the isochoric pressure search technique.•The equilibrium data were measured at 0.05, 0.075, 0.10, 0.15, and 0.20 mass fraction TBPB.•Measurements were undertaken in the ranges of (281.5–291.4) K and (1.10–7.79) MPa.•TBPB has a promotion effect on semi-clathrate hydrate formation for the pure gas systems under consideration.