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

A thin and continuous NH2-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 NH2-MIL-53. Results showed that the thin NH2-MIL-53 layer on ammoniated PVDF hollow fiber was inter-grown with thickness of only about 8 mu m. 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/CO2 increased 330 and 5.46 times respectively. The prepared NH2-MIL-53/PVDF hollow fiber membrane exhibited excellent H-2 permeance of 54.20 x 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/CO2, H-2/O-2, H-2/N-2 and H-2/CH4, respectively. The composite membrane can also efficiently separate the H-2/CO2 mixture with H-2 permeance of 42.13 x 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. (C) 2015 Elsevier B.V. All rights reserved.