Carbon dioxide absorption using a phase transitional alkanolamine–alcohol mixture

Some alkanolamine–alcohol mixtures separate into a CO2 rich phase and a CO2 lean phase after the absorption of CO2, which makes possible a new approach to CO2 capture. In this study, CO2 absorbent solutions with various concentrations of monoethanolamine (MEA) and diethanolamine (DEA) were prepared by mixing them with alcohol. The CO2 absorption capacities of the alkanolamine–alcohol mixtures were investigated by using a semi-batch reactor at 313 K. The species distributions of the absorbents were identified in order to determine the CO2 absorption mechanism of these solutions. Although the CO2 absorption capacities of the phase transitional absorbents are lower than that of aqueous solutions, we conclude from our experimental results that the phase transitional solutions have the economic advantages, and in particular lower regeneration energies, because only the CO2-rich phase needs to be transported to the stripper.