Intramolecular hybrid diamine DMAPA/n-PeOH/H2O biphasic absorbent for CO2 absorption through combining zwitterion and base-catalyzed hydration mechanism

Biphasic solvents can decrease the regeneration energy of CO2 capture. As an intramolecular hybrid diamine, 3Dimethylaminopropylamine (DMAPA) had a primary amino group and a tertiary amino group, which could absorb CO2 by combining zwitterion and base-catalyzed hydration mechanism. The derived DMAPA/n-PeOH/ H2O biphasic absorbent possessed high CO2 absorption capacity (1.46 mol/mol) and large CO2-rich phase loading (6.27 mol/L), which were superior to existing mixed amine systems. At 393.15 K, this system had a large desorption amount of 4.91 mol/L and a fast desorption rate (6.68 E-3 mol/L & sdot;s), which were 2.84 and 3.73 times of 30 wt% MEA. The associated total regeneration energy was reduced to 1.36 GJ/t CO2, only 34.1 % of MEA absorbent. The reaction mechanism and origin of phase separation were revealed by NMR analysis and quantum chemistry calculations. In addition, low viscosity and corrosiveness were revealed and conducive for industrial application.