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

• 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.

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.