Predicting phase-splitting behaviors of an amine-organic solvent–water system for CO2 absorption: A new model developed by density functional theory and statistical and experimental methods

Abstract

Carbon capture, utilization, and storage (CCUS) has become a promising approach for relieving CO2 effects on the environment. Moreover, CO2 absorption by phase-splitting solvents with a low regeneration energy has the potential for industrial CO2 capture. In this work, ionic logP of the product amine-CO2 was modeled to predict new phase-splitting solvents at the molecule level. The density functional theory method was used for structure calculation and descriptor generation. The genetic function approximation method was used for mathematical regression. The symmetry-adapted perturbation theory and reduced density gradient method were introduced to detect interaction mechanisms between ions and solvents. Furthermore, low-ion solubility tended to appear in long-chain alcohols, branched or ring structures, and aprotic solvents. A linear the demarcation line of biphase and monophase over phase-splitting diagram was drawn based on anion logP and cation logP as 0.984 * logPanion + logPcation = − 3.46.