Facile synthesis of molecular sieve membranes following “like grows like” principle

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Because of poor heterogeneous nucleation of MOF on the ceramic support surface, it is usually difficult to prepare defect-free metal-organic framework (MOF) layers as shape-selective membrane on the native ceramic supports by a direct solvothermal synthesis route. In the present work, inspired by “like dissolves like” principle, a simple and facile synthesis strategy was developed to prepare highly reproducible and permselective zeolitic imidazolate framework ZIF-8 membranes on the 1H,1H,2H,2H-perfluoroalkyltriethoxysilanes (POTS) modified α-Al2O3 disks. Attributing to the enhancement of surface hydrophobicity of the α-Al2O3 supports after POTS modification, hydrophobic ZIF-8 membranes are tending to grow well on the hydrophobic surface following the “like grows like” principle. Thus a well-intergrown ZIF-8 membrane with a thickness of about 20 µm has formed on the POTS-modified α-Al2O3 disks. The developed ZIF-8 membranes show high hydrogen selectivity and thermal stability. At 200 °C and 1 bar, the mixture separation factors of H2/CO2, H2/N2, H2/CH4, and H2/C3H8 are 15.8, 22.6, 40.6, and 549.3, with H2 permeances higher than 2.1 × 10−7 mol·m−2·s−1·Pa−1, which is promising for hydrogen separation and purification.