CO2 absorption enhanced by phase conversion under the synergistic interaction of proton transfer

Due to the proton transfer between aqueous solution of protic ionic liquids (PILs) and N,N,N',N'-tetramethyl-1,6hexanediamine (TMHDA), the liquid-liquid phases are gradually transformed into one phase during the absorption which is restored to two phases by carbon dioxide desorption, thus both the absorption and desorption processes were effectively intensified by phase conversion. The experimental results showed that CO2 load of TPH (composed of TMHDA, PILs and H2O) was 45% higher than that of PILs-H2O, as well as an obvious increase of absorption rate. Moreover, the regeneration energy consumption of TPH was only 2.10 GJ/tonCO2. The spectral analysis and molecular dynamics simulations revealed that the proton transfer was the key of phased conversion, and it was regulated by the synergistic interaction between PILs and TMHDA during the CO2 capture process. This kind of phase conversion strengthening absorbent with low viscosity is a useful way to achieve low energy carbon dioxide capture.