Biphasic systems of mutual amine solution with tunable phase separation for CO2 capture: Optimal compositions and volume of rich phase

Research and development of biphasic systems with significant absorption performance and low energy penalties is the key to achieving CO2 capture. In this paper, the effect of diethylenetriamine (DETA) and diethylethanolamine (DEEA) as amine solution dissolved in N-Methyl-2-pyrrolidone (NMP) and water with various molar ratios on the CO2 absorption was investigated. The formation of saturated solution including CO2-rich and lean phases was studied with scrutiny via 13C nuclear magnetic resonance (13C NMR). Under the optimal conditions, the CO2 loading of fresh absorbents could reach 0.97 and 0.95 mol CO2/mol amine solution with the final solid–liquid and liquid–liquid systems, respectively. Also, overcoming the tradeoff between the volume of rich-phase and CO2 loading as one of the biggest challenges in the biphasic liquid system occurred. The addition specific amount of NMP to the solution (when the molar ratio of NMP to solution is 1) decreased the rich phase volume to 50%, while the CO2 loading is 0.93 mol.mol−1.