Xinling Xu, Y. A. Liu, Heng-fei Cui, Jian Liu, Rui-tang Guo
Mitigating climate change requires efficient CO 2 capture technologies, yet conventional aqueous amines such as MEA suffer from high regeneration energy and chemical degradation. Phase-change amine absorbents (PCAAs) offer a promising alternative by undergoing liquid–liquid or liquid–solid phase separation upon CO 2 absorption, concentrating CO 2 in a small rich phase and lowering regeneration energy by ∼30–40%. This review outlines the development of PCAAs, their absorption mechanisms, phase-separation behaviors, and performance optimization strategies. Spectroscopic techniques ( 13 C NMR, IR, Raman) and molecular simulations (DFT, MD) have advanced mechanistic understanding, while thermodynamic modeling and process simulations guide solvent design and scale-up. Finally, by clarifying key challenges─such as incomplete elucidation of reaction pathways, mass-transfer limitations, and inconsistent evaluation criteria─this work proposes a comparative framework that links molecular mechanisms to process-level performance, offering more targeted insights to support PCAAs in surpassing conventional biphasic amine systems and advancing toward large-scale CO 2 capture applications.