A novel strategy for synthesizing the high-performance thin and compact sodalite zeolite membrane over rough α-Al₂O₃ support was developed. The synthesis involved the deposition of a layer of flaky MCM-22 zeolite crystals over support and the subsequent hydrothermal crystallization of sodalite zeolite. It was identified that the sodalite zeolite membrane possessed a thickness of ca. 700 nm with almost no defect, and a water/ethanol separation factor higher than 10 000 at a permeation flux of 4.4 kg·m^–2·h^–1 could be achieved. A possible mechanism for the formation of high-performance sodalite zeolite membrane was also proposed, which involved first the decomposition of MCM-22 zeolite crystals into small fragments containing double six-membered rings (D6R) and subsequently the nucleation and crystallization of sodalite initiated by the D6R-containing species over the surface of support from the strongly alkali synthesis sol. The study showed that the predeposition of a layer of flaky MCM-22 zeolite crystals over the surface of support was crucial for the generation of thin and compact sodalite membranes, as it not only improved the surface flatness but also led to the in situ nucleation and crystallization of sodalite zeolite crystals. This method combines 2D-material film-forming technology with 3D-material film-forming technology, thus providing a new approach for preparing thin and defect-free membranes.

中文翻译：

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MCM-22沸石诱导的方钠石沸石薄膜的合成

用于合成在粗糙的α-Al高性能薄且紧凑的方钠石的沸石膜的新策略₂ ö ₃支持开发。合成过程包括在载体上沉积一层片状MCM-22沸石晶体，以及随后对方钠石沸石进行水热结晶。可以确定，方钠石沸石膜的厚度约为1μm。700 nm，几乎没有缺陷，在4.4 kg·m ^–2 ·h ^–1的渗透通量下，水/乙醇的分离系数高于10000可以实现。还提出了形成高性能方钠石沸石膜的可能机制，该机制包括首先将MCM-22沸石晶体分解为包含双六元环（D6R）的小碎片，然后由氢氧化铝引发的方钠石成核和结晶。在强碱合成溶胶的载体表面上含有D6R的物质。研究表明，在载体表面上预沉积一层片状MCM-22沸石晶体对于薄而致密的方钠石膜的生成至关重要，因为它不仅改善了表面平整度，而且还导致了原位成核和方钠石沸石晶体的结晶。该方法将2D材料成膜技术与3D材料成膜技术相结合，