Synthesis of silicalite-1 membranes with high ethanol permeation in ultradilute solution containing fluoride

Defect free silicalite-1 membranes were successfully prepared on the surface of tubular mullite supports in ultradilute solution containing fluoride by hydrothermal synthesis. The typical molar composition of synthesis solutions was 1SiO2:0.2TPABr:0.2TPAOH:0.15NH4F:800H2O. The results of X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) of zeolite membranes were confirmed that the outer surface of support was fully covered with a randomly oriented and intergrown silicalite zeolite layer. The membrane prepared at 180 °C for 20 h showed high ethanol permselectivity for separation of ethanol/water mixtures. The flux and separation factor are achieved to 2.85 kg m−2 h−1 and 60 for 5 wt.% ethanol/water mixture at 60 °C, respectively.

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► Defect free silicalite-1 membranes prepared in ultradiluted solution containing fluoride.
► One-step rapid hydrothermal synthesis method.
► Synthesized membrane shows high permeation performance.
► The best pervaporation performance for a single-tube module of silicalite-1 membrane.