Protic/aprotic ionic liquids for effective CO separation using supported ionic liquid membrane.

Four ionic liquids (ILs) namely, 1-butylsulfonate-3-methylimidazolium P-toluene sulfonate ([BSmim][tos]), 1-butylsulfonate pyridine P-toluene sulfonate ([BSmpy][tos]), 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) and 1-butylpyridine chloride ([Bpy][Cl]) were synthesized for the effective separation of gases CO/N and CO/CH through supported ionic liquid membranes (SILMs). ILs were confirmed by NMR and FTIR spectroscopy, and their characteristics and physical properties were studied. The ILs were immobilized on the porous hydrophobic 200 μm thick polyvinylidene difluoride (PVDF) support. Pure and mixed gas separation performances of the prepared SILMs were analyzed in a custom-built gas permeation unit. The SILMs were stable up to 0.6 MPa at room temperature without leaching the ionic liquid. [BSmim][tos] was recorded to have the highest solubility coefficient and permeability for CO among other ILs. At 0.5 MPa, for pure CO/N and CO/CH, IL [BSmim][tos] was observed with selectivities of 56.2 and 47.5, respectively. Based on the SILMs separation performance, the ILs synthesized for this work can be ranked as [BSmim][tos] > [BSmpy][tos] > [Bmim][Cl] > [Bpy][Cl]. Moreover, the exceptionally high selectivity values of [BSmim][tos] and [BSmpy][tos] confirms the potential use of ILs for CO separation through SILMs.