Abstract Hydrophobic MFI zeolite membranes are perm-selective to organic compounds over water and offer applications for organic/water separations. However, reproducible synthesis of MFI zeolite membranes with high organic selectivity remains a challenge. This paper reports a new synthesis method consisting of dual-layer seeding and varying-temperature secondary growth for the synthesis of hydrophobic MFI zeolite membranes on alumina hollow fiber supports. The effects of seeding method, seed particle size, seed size ratio, and variable temperature/time profile on the microstructure, hydrophobicity and gas perm-selectivity of the membranes are investigated leading to identification of optimum seed structure and secondary growth conditions for synthesis of MFI zeolite membranes with high ethanol/water separation performance. The high-performance MFI zeolite membrane has microstructure consisting of a thin, fully inter-grown, and dense top zeolite layer responsible for high selectivity, and a porous low inter-grown bottom zeolite layer minimizing resistance and retarding aluminum transfer from the support to zeolite. The best hollow fiber supported MFI zeolite membrane with a Si/Al ratio of 187 exhibits ethanol/water pervaporation separation factor of 160 with total flux of 3 kg m−2 h−1.

中文翻译：

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双层接种变温二次生长合成高性能MFI沸石中空纤维膜

摘要 疏水性 MFI 沸石膜对水的有机化合物具有选择性渗透性，可用于有机/水分离。然而，具有高有机选择性的 MFI 沸石膜的可重复合成仍然是一个挑战。本文报道了一种新的合成方法，该方法由双层晶种和变温二次生长组成，用于在氧化铝中空纤维载体上合成疏水性 MFI 沸石膜。研究了接种方法、种子粒径、种子粒径比和可变温度/时间曲线对膜的微观结构、疏水性和气体渗透选择性的影响，从而确定了合成 MFI 的最佳种子结构和二次生长条件具有高乙醇/水分离性能的沸石膜。高性能 MFI 沸石膜的微观结构由薄的、完全相互生长的、致密的顶部沸石层组成，负责高选择性，以及多孔低相互生长的底部沸石层，最大限度地减少阻力并阻止铝从载体转移到沸石. 最好的中空纤维支撑 MFI 沸石膜，Si/Al 比为 187，乙醇/水渗透蒸发分离系数为 160，总通量为 3 kg m-2 h-1。