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It is difficult to control the heterogeneous nucleation and growth of crystals on porous supports, the preparation of thin ZIF-8 membranes is still extremely challenging. Herein, a two-dimensional transformation strategy is demonstrated for constructing a ZIF-8/GO 'sandwich' composite membrane with a thickness of ∼0.9 μm, which was prepared from Zn-EG-AC (EG: ethylene glycol, AC: CH 3 COO-groups, abbreviated as ZnEG) on alumina hollow fiber support for the first time by precursor conversion method in 2-methylimidazole methanol solution. The effects of the amount of precursor, reaction time and membrane thickness on the membrane structure and H 2 /CO 2 separation performance are explored. The sieving effect of ZIF-8 and the adsorption effect of 2-methylimidazole rings on CO 2 , as well as the strong interaction between GO and CO 2 hinder the permeation of CO 2 into the membrane, thus exhibiting a good H 2 /CO 2 ideal separation selectivity of 30.8 with the H 2 permeance of 1.36 × 10−7 mol·Pa−1·m−2·s−1 under the optimized preparation conditions. The separation factor of the equimolar H 2 /CO 2 binary-mixture gases stabilizes to ∼25 after 30 h. This precursor conversion strategy is expected to be extended to other MOF/graphene oxide (GO) composite membrane systems. Thin ZIF-8/GO sandwich composite membranes can be obtained on alumina hollow fiber supports by a precursor conversion strategy. [Display omitted] • Thin ZIF-8/GO sandwich composite membranes on alumina hollow fibers. • Zinc glycol/GO precursors to ZIF-8/GO membranes by precursor conversion. • The thickness of the high quality ZIF-8/GO membrane is only 0.9 μm. • ZIF-8/GO membranes have considerable H 2 /CO 2 separation selectivity. [ABSTRACT FROM AUTHOR]

Zeolite membranes are broadly applied in separation, catalysis, and sensor, yet challenges remain in the preparation process. The design of support is an important component to simplify the synthesis protocol and improve the repeatability. Herein, we present a facile and universal strategy to fabricate high-performance zeolite membranes via engineering the skeleton of hollow fiber supports, on which a variety of high-performance zeolite membranes (e.g., MFI, LTA and FAU) can be obtained just by in-situ crystallization without any modification. The "reactive" support is fabricated by implanting zeolite crystals (e.g., NaA) in the precursor of porous ceramic alumina support. Being dissolved under alkaline condition of the synthesis solution, the zeolite calcination transformant (e.g., NaA-Cal) produced in the support during sintering process can effectively form nucleation sites on the support surface, and continuously provide active species to ensure the continuity of the membrane. This study contributes new insights into the importance of supports for high-performance zeolite membranes. Meanwhile, the synthetic methodology is expected to expand the preparation method of zeolite membranes and promote the large-scale application of zeolite membranes. [Display omitted] • Implanting zeolite crystals into the ceramic slurry for preparation of versatile supports. • A variety of high-performance zeolite membranes can be obtained on the support. • No modification or repeated synthesis is needed using the versatile support. [ABSTRACT FROM AUTHOR]