CO₂/N₂ separation using alumina supported membranes based on new functionalized ionic liquids

In the present work, supported liquid membranes based on three ionic liquids (ILs) (1-(2-aminoethyl)-3-methylimidazolium trifluoromethanesulfonate ([AEMIm]Tf), 1-(2-aminoethyl)-3-methylimidazolium tetrafluoroborate ([AEMIm]BF₄) and trioctylmethylammonium anthranilate ([TOMA])), used as mobile phases, were studied in the separation of carbon dioxide from nitrogen. The IL chemical structures and thermal properties were confirmed by spectroscopic techniques and thermogravimetric analysis (TGA), respectively. The IL homogeneous distribution of the impregnation on alumina tubular supports was determined by scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX). Permeation tests were carried out using pure gases at 30 °C and 1 bar. The amino-functionalized ILs, two of them in the cation, [AEMIm]BF₄ and [AEMIm]Tf, and the other one in the anion, [TOMA]An, reacted with CO₂, leading to the formation of carbamates. [TOMA]An, which has the amine group at the anionic part, showed the best permselectivity, reaching a selectivity of 70.