Three-component CO2 binding organic liquids for efficient and reversible CO2 capture: Effect of molar ratio of component on mechanism.

[Display omitted] • A series of three-component CO 2 -BOLs composed of superbases, alcohols and amines were synthesized for CO 2 absorption. • DBN/EG/MEA has good CO 2 absorption properties and water resistance. • Different ratios of DBN/EG/MEA have different absorption mechanisms, in which the superbase plays a crucial role. • Density functional theory (DFT) verified the absorption mechanism. CO 2 binding organic liquids (CO 2 -BOLs) belong to the CO 2 -triggered switchable polar solvents (SPSs) in switchable solvents (SSs), which can be used as green non-aqueous CO 2 absorbers. A three-component CO 2 -BOLs composed of superbase, alcohol and amine are introduced in this study. After investigating the effects of different alcohols and amines on the ternary system, the optimum combination of DBN/EG/MEA was determined. In addition, considering the sensitivity of superbase to CO 2 in CO 2 -BOL system, the absorption performance of DBN, DBU and TMG with different pKa in this combination was compared. The temperature, molar ratio and water content of DBN/EG/MEA were explored, and it was found that the optimal absorption was 0.267 g CO 2 /g solvent at the molar ratio of 1/1/3, 40 °C and 1 bar. Interestingly, different absorption effects are observed when the molar ratio of each component in the ternary system is increased. With the increase of DBN and MEA, the absorption of CO 2 increased, but the increase of EG is not conductive to CO 2 absorption. Based on nuclear magnetic spectroscopy analysis and quantum chemical calculation, it is found that DBN/EG/MEA with different ratios presents different absorption mechanisms. When the content of DBN is increased to a certain extent, EG which does not have absorptive activity can be activated, so that both MEA and EG can absorb CO 2. In addition, the CO 2 -BOLs synthesized in this study exhibited excellent recoverability. It provides a valuable reference for further design and synthesis of efficient CO 2 capture solvents. [ABSTRACT FROM AUTHOR]