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

Wu, Xiaocao, Liu, Chuanyao, Caro, Jürgen, Huang, Aisheng
Journal of membrane science 2018 v.559 pp. 1-7
aluminum oxide, artificial membranes, carbon dioxide, ceramics, coordination polymers, hydrogen, hydrophobicity, methane, propane, thermal stability
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.