Hydrate phase equilibria of the guest mixtures containing CO2, N2 and tetrahydrofuran

The three-phase, hydrate-water-rich liquid–vapor (HLV), equilibria of the binary guest mixtures containing CO2 and N2 were determined at the temperature range of 272–275 K and different compositions of vapor phase. In addition, two phase equilibria of hydrate and vapor were also measured at three isothermal conditions of 274, 277 and 278 K. The resulting P–x diagram indicates that CO2 can be more contained than N2 in the hydrate phase. More than 96 mol% CO2 in the mixed hydrate phase was obtained from a gas mixture of 17 mol% CO2 and 83 mol% of N2 at 274 K. The addition of tetrahydrofuran (THF) as a hydrate promoter extended hydrate stability region by elevating equilibrium dissociation temperature and lowering pressure. The overall hydrate equilibrium results were found to agree well with the calculated ones.