Fluoride‐assisted ultradilute precursor synthesis of defect‐free thin FAU zeolite membrane for pervaporation dehydration

Abstract Pervaporation (PV) is a promising alternative to distillation for biofuel dehydration, yet fabricating thin, defect‐free zeolite membranes remains challenging. In this work, a synergistic strategy combining nanoseeds, fluoride mineralizers, and ultradilute precursors was developed to construct high‐quality faujasite (FAU) membranes. Nanoseeds provided compact seed layers, fluoride promoted crystal intergrowth while suppressing non‐selective channels, and ultradilute precursors slowed crystallization yielding ~2.4 μm membranes with low defect density. Performance analysis confirmed that PV separation followed an adsorption‐diffusion mechanism. The optimized membrane achieved excellent fluxes of 3.70 kg/(m 2 h) with a separation factor of 1520 for a 10 wt% water/isopropanol mixture and 6.01 kg/(m 2 h) with a separation factor of 742 for a 20 wt% water/ n ‐butanol mixture. These results surpassed the results of previously reported membranes and demonstrated how this cooperative strategy provides a viable pathway for scalable fabrication of defect‐free thin zeolite membranes.