Separation of toluene from gas phase using supported imidazolium ionic liquid membrane

Investigation on utilization of supported ionic liquids membranes for hydrocarbon separation from the gas phase was performed. Properties of membrane phase, wettability of supports, swelling effects and solubility of toluene were taken into account. Toluene permeation rates were significantly higher than those of pure nitrogen, the selectivity in a range of 17-341 was satisfying for separation. Despite the increase of viscosity resulting from increasing alkyl chain length of imidazolium bis(trifluoromethylsulfonyl)imide [Tf2N] ionic liquids, permeation of toluene increases due to the higher hydrophobicity and therefore separation is solubility-controlled. However, imidazolium trifluoromethanesulfone [TfO] ionic liquids did not follow the same path. Nevertheless, toluene was successfully separated from N2/toluene gas stream using ionic liquid membranes based on both [Tf2N] and [TfO] yet, in the light of the obtained results and literature data these systems are highly recommended for VOCs separation from gas phase.