Phase equilibrium for ionic semiclathrate hydrate formed with CO2, CH4, or N2 plus tetrabutylphosphonium bromide

The article describes the equilibrium conditions for the semiclathrate hydrates formed in the following three ternary systems, CO2 + tetrabutylphosphonium bromide + water system, CH4 + tetrabutylphosphonium bromide + water system, and N2 + tetrabutylphosphonium bromide + water system. The experiments were performed at temperatures between 282.6 and 291.6 K, at pressures between 0.15 and 5.10 MPa with tetrabutylphosphonium bromide aqueous solution of wTBPB = 0.35, where wTBPB denotes the mass fraction of tetrabutylphosphonium bromide, respectively. The equilibrium pressure at a given temperature was lower in the order of CO2, CH4 and N2 thereby indicating the possibility of capturing CO2 from the CH4 + CO2 and N2 + CO2 mixtures.