Carbon sequestration — is an important method to achieve carbon neutrality and resist climate change. Burying CO2 in the depth of geological structure and solidifying it into hydrate is a promising carbon sequestration technology. The development of hydrate- based CO2 sequestration requires greater CO2 storage capacity and mild thermodynamics. In this study, 1,3- dioxolane (DIOX) was introduced as the hydrate thermodynamic promoter. The effect of the DIOX-water system lowers than the stoichiometric concentration on the formation of CO2-DIOX mixed hydrate was evaluated by measuring phase equilibrium and formation kinetics. The results show that DIOX shows thermodynamic promotion to CO2 enclathration. Even at the ultra-low concentration (0.15 mol%), the system still maintains a phase equilibrium pressure shift of 0.45 MPa. Compared with the system of 5.56 mol%, the system of 3.00 mol% has better formation kinetics; the 0.15 mol% system still maintains considerable CO2 storage capacity (56.0 mmol/mol). The study of low concentration DIOX not only has a practical significance of the passive decline in promoter concentration on large-scale carbon sequestration but also meets the requirements of environmental protection and economy in the use of the thermodynamic promoter.
Keywords CO2 hydrate, 1,3-dioxolane, Phase equilibria, Kinetics, CO2 sequestration