New insight and evaluation of secondary Amine/N-butanol biphasic solutions for CO2 Capture: Equilibrium Solubility, phase separation Behavior, absorption Rate, desorption Rate, energy consumption and ion species

Effective phase-change solvent system, n-methyl-2-hydroxyethylamine (MAE) + water-insoluble alcohol + H2O, was developed for CO2 capture. First, a preliminary screening of several alcohols was carried out and showed that the MAE/n-butanol/water system had the potential to become an excellent phase change absorbent. Then, through phase change experiment, absorption experiment, desorption experiment, and theoretical energy consumption analysis, the MAE:n-butanol:water ratio of 3:4:3 possessed the most impressive CO2 capture performance. Theoretical calculation of CO2 desorption energy consumption showed that in comparison with 30 wt% monoethanolamine (MEA), 50% of reboiler heat duty can be reduced in case of the 3:4:3 system. In addition, equilibrium phase diagram of the three components showed that concentration of n-butanol significantly affected the phase separation. The two-phase species distribution after phase separation was determined using Nuclear magnetic resonance spectroscopy (NMR). This work also shows that temperature has influence on absorption and desorption performance. Finally, the absorbent stability test during absorption–desorption process confirmed that MAE/n-butanol/water absorbent had a great potential for capturing CO2.