Investigation of hydrate formation by synthetic ternary gas mixture with cyclopentane(C5H10)

Abstract Cyclopentane (CP) is an alkane that combines with water to form hydrates. Here, we investigate the hydrate thermal dynamics and formation kinetics of a synthesized ternary gas mixture of CH4/CO2/N2 with CP additives. The results indicated that CP shifts the phase equilibrium conditions of ternary gas mixture hydrates to higher temperature and lower pressure. Under a constant pressure, the largest temperature offset can be approximately 20 K. Meanwhile, the ternary gas mixture of CH4/CO2/N2 formed structure II hydrates with added CP. The kinetics study indicated that the hydrate reaction started immediately when accompanied by stirring. The consumption of CO2 gas was greater than that of CH4 and N2. The ratio of the volume of CP to the volume of water had a considerable influence on the effective reaction time, CH4 recovery factor (RCH4), and CO2 split ratio (SCO2) under all experimental conditions. RCH4 and SCO2 were higher when the CP-to-water volume ratio was 0.308. The largest values of RCH4 and SCO2 were 3.098 and 0.908, respectively, when the CP-to-water volume ratio was 0.308 at 7.0 MPa and 280.1 K. These results favor the use of CP as an additive to separate CO2 and purify CH4 in gas mixtures.