Iron-based ionic liquid ([BMIM][FeCl4]) as a promoter of CO2 hydrate nucleation and growth

Hydrate technology is a promising alternative method for carbon dioxide (CO 2 ) capture and storage from flue gas . In order to promote the hydrate growth rate and increase gas storage capacity, CO 2 hydrate nucleation and growth induced by iron-based ionic liquid ([BMIM][FeCl 4 ]) was studied with 400 rpm rotation speed at a temperature of 274.15 K and initial pressure of 5.0 MPa in this work. The induction time of CO 2 hydrate formation was decreased by 52.8% and the storage capacity of CO 2 hydrate was increased by 13.7% in 25.0 g/L [BMIM][FeCl 4 ] solution. The local hydrogen bonds are strengthened by the combination interaction between the complex anion ([FeCl 4 ] − ) and water (H 2 O) molecules, which is favorable to the ordered arrangement and the proton exchange rate of H 2 O molecules during the hydrate nucleation. Besides, large mass transfer channels are formed by the large molar volume and regular tetrahedral structure of [FeCl 4 ] − during the hydrate growth, which improves the diffusion rate of CO 2 and H 2 O molecules in the solution to promote the hydrate growth. Distribution of lipophilic cation and hydrophilic anion with a large molecular volume of [BMIM][FeCl 4 ] at the gas-liquid interface hinders the formation of cage structure of H 2 O molecules.