The effect of chemical structures of cyclic amino acid type ionic liquids as CO2 carriers on facilitated transport membrane performances

Four kinds of amino acid ionic liquids (AAILs) with different cyclic amino acids were synthesized and used as CO2 carriers of facilitated transport membranes (FTMs) to investigate the effect of their chemical structure on the CO2 permeability. The cyclic AAILs showed low viscosities after CO2 absorption. The CO2 permeability of the FTM containing the cyclic AAIL with greater electron density showed better CO2 permeability owing to the higher CO2 absorbability and low viscosity. Because the viscosities of the investigated AAILs were relatively low, the dominating factor of the CO2 permeation resulted from the electron density of the amino group.