Review of research progress and stability studies of amine-based biphasic absorbents for CO2 capture

Chemical absorption is a mature technology for CO2 capture from flue gas, but its high energy consumption hinders industrial applications. Phase-change absorbents (PCAs) are an innovative technology for CO2 capture that can lower energy consumption and cost compared to traditional organic amine absorbents. This article reviews the recent research on CO2 capture using amine-based PCAs that can undergo liquid–liquid phase separation (LLPS), and introduces two widely studied absorbents, namely amine-blended biphasic absorbents, and physical-solvent biphasic absorbents, and compares their capture performance, reaction mechanism, and phase separation mechanism with conventional solvents. The article further discusses the stability problems that exist with PCAs, including degradation and volatilization. It scrutinizes the degradation mechanism of certain amine solutions and proposes potential mitigation strategies. Lastly, the limitations and optimization potential of biphasic solvents, as reported in prior studies, are evaluated to inspire the advancement of innovative absorbents.