Study of Physical Absorption of Carbon dioxide in imidazolium-based Ionic liquids

In this study, the solubility of CO2 in imidazolium-based ionic liquids with different anions has been compared at 323.15 K in mole fraction and molality scals. The anions considered in this study are [PF6]–, [OTf]–, [BF4]–, [TF2N]–. Results show that solubility of CO2, expressed in mole fraction scale, in the following sequence: [C8mim][TF2N] > [C4mim][OTF] > [C8mim][PF6] > [C2mim][OTF] > [hC2mim][BF4] [C2mim][BF4]. When the concentration is switched to molality scale, the solubility of CO2 in the ionic liquids in the following sequence: [C8mim][TF2N] ≈ [C8mim][ PF6] > [C4mim][OTF] > [C2mim][OTF] > [C2mim][BF4] > [hC2mim][BF4]. The experimental data at 323.15 K were correlated by using the Pitzer’s model. The Pitzer’s model has a good predict for Ionic Liquids + carbon dioxide systems in this work.

Keywords:

carbon dioxide , ionic liquids , gas sweetening , acid gas , modeling