Role of 1-methylimidazole in regulating the CO2 capture performance of triethylenetetramine-based biphasic solvents

Biphasic solvents are promising candidates for CO 2 capture for low regeneration energy consumption. In this study, a novel phase splitter 1-methylimidazole (1-MI) was proposed for triethylenetetramine (TETA) aqueous solvent. 1-MI was proved to act as a phase splitter to induce the phase separation and as an absorption promoter to enhance the absorption rate. By tuning the concentrations of TETA and 1-MI, good phase separation performance was obtained in TETA-1-MI biphasic solvent, achieving a CO 2 -rich phase loading of 5.41 mol/L. 13 C NMR revealed that the upper layer was the CO 2 -lean phase, containing 1-MI and a small amount of water, while the lower layer was the CO 2 -rich phase and mainly comprised of TETAH + and TETA-carbamate. The kinetics results based on the double-film theory indicated that the CO 2 absorption rate was mainly controlled by the gas film mass transfer resistance at lower CO 2 loading and then by liquid film mass transfer resistance when CO 2 loading was higher than 1 mol/L. Owing to the good phase separation behavior triggered by 1-MI, the regeneration heat of TETA-1-MI was 2.26 GJ/t CO 2 , which was comparable to that of the second-generation solvents, and 43.5 % lower than that of 5 M monoethanolamine (MEA). The present findings indicated that TETA-1-MI had a large loading capacity, high absorption rate, and low energy consumption, which can serve as a novel candidate for CO 2 capture.