Highly Efficient Absorption of CO₂ by Protic Ionic Liquids-Amine Blends at High Temperatures

Abstract

In view of the increasingly serious harm of CO₂ to the environment, it is highly desirable to develop effective CO₂ absorbents. In this work, we demonstrated an efficient absorption of CO₂ by blends of protic ionic liquids (PILs) plus amines. The density and viscosity of investigative four PILs-amine mixtures were measured. By systematically studying the effects of the solution ratio, temperature, CO₂ partial pressure, and water content on the absorption of CO₂, it is found that the 3-dimethylamino-1-propylamine acetate ([DMAPAH][OAc]) plus ethanediamine (EDA) mixture shows the highest CO₂ uptake of 0.295 g CO₂ per g absorbent at 50 °C and 1 bar and a further increase in the absorption of CO₂ to 0.299 g/g by adding water with a mass fraction of 20%. Furthermore, the absorption mechanism of CO₂ in the presence and absence of water has also been investigated by FTIR and NMR spectra.