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. (C) 2017 Elsevier Ltd.