Perfluorocarbon-based supported liquid membranes for O2/N2 separation

•Perfluorotributylamine (PFTBA) supported on porous alumina was used as a liquid membrane.•The separation of O2/N2 and H2/N2 at 40 °C was higher than those of other liquid membranes.•The O2/N2 separation factor was ∼60 with an O2 permeance of 8 × 10−10 mol m−2 s−1 Pa−1.•The permeance of the membrane correlated with the gas molecular size as H2 > O2 > N2.

Air separation is an important commercial process because oxygen and nitrogen are used in several vital industrial processes. This paper reports the implementation of perfluorotributylamine (PFTBA) imbued in porous alumina tubes as a supported liquid membrane to carry out the separation of O2 and N2. The PFTBA-supported membrane reached an average O2/N2 selectivity of 60 with an O2 permeance of 8.0 × 10−10 mol m−2 s−1 Pa−1. It is shown that the membrane’s selectivity increases as the temperature increases but the stability of the membrane is reduced. Moreover, the separation of H2 and N2 was studied to provide insight on the functioning of the membrane and a H2/N2 selectivity of 100 was observed with a H2 permeance of 1.0 × 10−9 mol m−2 s−1 Pa−1. The permeance order was H2 > O2 > N2, so the size of the permeating species was found to be an important contributor to the permeance. PFTBA presents an excellent separation performance when compared with conventional supported ionic liquid membranes (SILMs). For instance, 1-ethyl-3-methylimidazolium tetrafluoroborate [emim][BF4] showed a maximum O2/N2 selectivity of 6 and permeance of 3.4 × 10−12 mol m−2 s−1 Pa−1.

Graphical abstractSupported liquid membrane: nitrogen/oxygen selectivity = 60.Figure optionsDownload full-size imageDownload as PowerPoint slide