Transfer printing platelike MFI crystals as seeds for the preparation of silicalite-1 membranes

Abstract

High aspect ratio zeolite crystals and their seeding on support are of high desire for the fabrication of oriented zeolite membranes. Here, platelike MFI crystals, as zeolite seeds, are successfully seeded on a α-Al2O3 disk support through a transfer printing method. Firstly, platelike MFI crystals are spread on a flat substrate pre-coated with films of polyvinyl alcohol (PVA) and a fluoropolymer (4200UR) followed by coating a polymethyl methacrylate (PMMA) film. After dissolving the PVA film, the free-standing sandwich-like 4200UR-MFI-PMMA film is transferred onto the support. Then, platelike MFI crystals are successfully seeded after removing the organic species by calcination. Finally, highly (h0h)-oriented, dense and continuous silicalite-1 membranes are fabricated after a secondary growth in a zeolitic synthesis system, confirmed by XRD and SEM techniques. Binary separation of butane isomer has been performed on the silicalite-1 membranes prepared with different synthesis time, achieving a n-butane permeance and a separation factor of 2.27 × 10−7 mol m−2 s−1∙Pa−1) and 28.8 for an equimolar n-butane/i-butane mixture at 343 K, respectively.