Carbanion-based ionic liquids are proposed and utilized as the key components for the construction of five super-nucleophilic deep eutectic solvents (SNDESs) in the paper. The super-nucleophilic nature of carbanion-based ILs is found to enable the capture of CO2 with large absorption capacity. However, the absorption is very slow in the IL due to high viscosity. The synergy of carbanion siting and hydrogen bonding is found to enable high and fast absorption of CO2 in [N2222][CH(CN)2]-ethylimidazole (Eim), and a synergistic absorption mechanism is proposed and validated from spectroscopic analyses and quantum calculations. The enthalpy change of CO2 absorption in [N2222][CH(CN)2]-Eim is calculated to be -39.6 kJ/mol according to the thermodynamic model, and the moderate value implies that both absorption and desorption of CO2 in the DES are favored and well balanced. The synergism of carbanion and hydrogen bond mediated by SNDESs provides a novel insight into the efficient CO2 capture.

With the catalytic induction of EG, anhydrous DMEA shows CO2 absorption performance via chemical binding and physical storage under normal pressure. Among the absorbents, pure DMEA can hardly absorb CO2 directly but when the zwitterionic alkylcarbonates are formed between CO2 and DMEA-EG which can be characterized by 13C NMR and FTIR, the absorption rate of CO2 will be improved at this time. An increasing the CO2 loading as the mass fraction of EG in DMEA-EG, 90wt.% EG captures up to 0.72 mol/mol. The amount of chemically bound and physically stored is directly dependent on temperature, within the range of 293 to 323K, an absorption-regeneration cycle can be formed in a closed vessel because of the zwitterion DMEA-EG-CO2 is unstable at the higher temperature. In other words, DMEA-EG-CO2 can be easily regenerated upon appropriate depressurization or heating, corresponding thermodynamic calculations prove that the regenerative energy of DMEA-EG-CO2 is 25.49kJ/mol.

A document by Meisi Chen. Click on the document to view its contents.