Development of phase separation solvent for CO₂ capture by aqueous (amine + ether) solution

Phase separation solvents for CO₂ absorption have been designed which transform into two liquid phases after CO₂ absorption. We studied seven types of amines and one type of ether-mixed solvents and observed that there are three types of phase phenomena, namely, no phase separation, phase separation with CO₂ scrubbing, and initially immiscible. We also observed that these types can be classified using the hydrophobicity of the amine. The solubility of CO₂ was measured in the phase separation solvent. In the lower-pressure region, the solvent formed a single liquid phase. When the amount of CO₂ in solution reached a separation point, the solvent separated into two liquid phases.