Chemisorption of carbon dioxide in imidazolium based ionic liquids with carboxylic anions

The absorption ability of carbon dioxide in ionic liquids (IL) containing a basic anion like acetate was investigated and compared to common ionic liquids as well as nitrogen data. Thereby, the IL showed chemisorption due to a formation of carboxylate at the imidazolium ring. The results obtained from [EMIM] [pivalate] are promising, since the IL could be completely recovered with a simple evacuating step, and without further heating, while having a similar absorption ability than [EMIM] [OAc].From the temperature dependency of the carbon dioxide absorption in [EMIM] [OAc] it can be seen that the solvation enthalpy is much smaller compared to common ionic liquids with physical absorption.Furthermore, the addition of the superbase DBU to [EMIM] [OAc] increased the CO 2-loading capacity.