Aiming at developing improved liquid phases for facilitated CO2 separation from post-combustion processes through supported ionic liquid membranes (SILMs), this work explores the use of binary equimolar IL mixtures containing a common imidazolium cation combined with tricyanomethane and five amino acid-based anions, glycinate, l-alaninate, taurinate, l-serinate and l-prolinate. The CO2 and N2 permeation properties of the prepared SILMs were determined at T=318.15 K and several trans-membrane pressure differentials. The results indicate that as the trans-membrane pressure differential decrease, the CO2 permeability through the SILMs containing the IL mixtures approaches or even surpasses that of the pure [C2mim][C(CN)3]. Similarly, the CO2/N2 permselectivity significantly increases, meaning that the prepared IL mixtures work as CO2 carriers under low trans-membrane pressure differentials, facilitating the flux of CO2 through SILMs. In particular, large CO2 permeabilities and high CO2/N2 permselectivities were obtained for the IL mixtures containing l-alaninate and taurinate anions, indicating that they can be considered as promising and efficient liquid phases for facilitated CO2 separation.
- Amino acid- and cyano-based anions
- CO/N separation
- Facilitated supported ionic liquid membranes
- Gas transport
- Ionic liquid mixtures