Evaluation of phase separation behavior of amine + organic solvent + H2O phase change absorbents

Abstract

CO2 phase change absorbents, CPCAs, have attracted growing interest due to their potential of energy saving for CO2 capture. Unclear phase separation pattern is challenging for the efficient development of CPCAs. The effect of organic solvents properties on the phase separation process was investigated in this work. The difference of ion–dipole interaction between ion-organic solvent and ion-water was used to illustrate the phase separation behavior. Relative dielectric constant and ET(30) to water were proposed as indicators to provide guidance on the selection of organic solvents in CPCA. The organic solvents with less dielectric constant and ET(30) relative to water, were tend to phase split, and higher ion distribution coefficient obtained. The developed MEA CPCAs showed larger CO2 cyclic capacity than 30wt.%MEA, among which 1,4-dioxane CPCA was 49.0% higher than benchmark MEA solution.