The selection of ionic liquids (ILs) is crucial to the performance of new absorption working pairs (ILs-CO2) and cycle characteristics of absorption refrigeration. The properties of ILs absorbing CO2 are affected directly by ILs’s species

cation structure

temperature and CO2 partial pressure. In this paper

an experimental system was designed and built to measure CO2 solubility in the ILs. On the principle of low viscosity and better absorption performance

four imidazole bis trifluoromethanesulfonimide ILs ([emim][Tf2N]

[bmim][Tf2N]

[hmim][Tf2N] and [omim][Tf2N]) were selected and the CO2 solubility in them was measured within 2.0 MPa to 5.0 MPa at 298.15 K

313.15 K and 328.00 K

respectively. The results show that imidazole bis trifluoromethanesulfonimide ILs have a better performance of absorbing CO2; the longer the alkyl chain of the same family ILs is

the larger the solubility is

and the CO2 solubility increases in the order of [emim][Tf2N]