Poly (ether-block amide) thin-film membranes containing functionalized MIL-101 MOFs for efficient separation of CO2/CH4

Abstract

In this study, a post-synthesis modification method was used to graft tetraethylenepentamine (TEPA) on MIL-101(Cr) metal organic framework (MOF). The post-modified amine grafted MIL-101(Cr) was incorporated into poly (ether-block amide) (Pebax® 1657) to fabricate thin-film nanocomposite (TFN) membrane. A series of single gas permeation experiments were carried out through the synthesized membranes to evaluate the effect of amine functional groups on the gas permeability and selectivity. BET, FT-IR, XRD, and FE-SEM results indicated that the amine groups were grafted on MIL-101(Cr) successfully. Moreover, the morphological studies of synthesized membranes demonstrated the formation of uniform and non-defected composite selective layer over the polyethersulfone sublayer. Gas permeation tests revealed that the best performance of TFN membranes obtained for sample containing 5 wt% TEPA-MIL-101 at 4 bar; in which the CO2 permeability increased by 63% (34.6 Barrer) as compared with Pebax neat membrane (21.8 Barrer). Meanwhile, an outstanding CO2/CH4 selectivity of 46.3 was achieved, which was 110% greater than the parent neat Pebax membrane (21.1). The results showed that TFN membranes have great potential in CO2 separation at low pressure.