Preparation of continuous NH2–MIL-53 membrane on ammoniated polyvinylidene fluoride hollow fiber for efficient H2 purification

Abstract A thin and continuous NH 2 –MIL-53 layer composed of Al(III) and 2-amino terephthalic acid has been successfully deposited on an ammoniated polyvinylidene fluoride (PVDF) hollow fiber under harsh synthetic conditions in N,N-dimethyl formamide (DMF) precursor solution at 423 K. In order to enhance the solvent resistance and thermal stability of membrane, the hollow fiber was ammoniated by ethanediamine to become cross-linked. The amino groups formed on its surface provided high-density heterogeneous nucleation sites for strong adhesive growth of NH 2 –MIL-53. Results showed that the thin NH 2 –MIL-53 layer on ammoniated PVDF hollow fiber was inter-grown with thickness of only about 8 μm. After activation by DMF at 423 K for 5 h and drying under vacuum at 423 K for 12 h, its permeance and ideal separation factor of H 2 /CO 2 increased 330 and 5.46 times respectively. The prepared NH 2 –MIL-53/PVDF hollow fiber membrane exhibited excellent H 2 permeance of 54.20×10 −7  mol s −1  m −2  Pa −1 as well as the high ideal separation factor of 30.37, 24.07, 27.85 and 27.31 for H 2 /CO 2 , H 2 /O 2 , H 2 /N 2 and H 2 /CH 4 , respectively. The composite membrane can also efficiently separate the H 2 /CO 2 mixture with H 2 permeance of 42.13×10 −7  mol s −1  m −2  Pa −1 and separation factor of 32.35, which showed to be the highest separation factors among those reported for polymer supported MOF membranes.