Study on the Performance of Diethylenetriamine and 2-Diethylaminoethanol Biphasic Solvent for CO2 Capture at High Amine Concentrations

To reduce the high regeneration energy consumption of conventional amine solvents, high-amine diethylenetriamine/2-diethylaminoethanol (DETA/DEEA) biphasic systems were investigated for postcombustion CO2 capture. The results showed that the DETA-DEEA system at 80% amine concentration had excellent partitioning performance, desorption rate, and cyclic loading at an absorption temperature of 40 °C and a desorption temperature of 120 °C. The regeneration energy consumption was only 2.42 GJ/t CO2, representing a 36.3% reduction compared to that of 30 wt % monoethanolamine (MEA). The biphasic solvent with a 70% amine concentration exhibited excellent absorption performance, while the lower liquid phase maintained a low viscosity, with a minimum of 53.8 mPa·s. Compared with low-concentration systems, high-concentration DETA-DEEA showed an enhanced absorption rate, greater CO2 loading, better cyclic loading, and favorable phase behavior with acceptable viscosity, underscoring its efficient capture potential.