Zeolites have extensively been applied in gas adsorption and separation, catalysis, and ion exchange thanks to their numerous interesting features. However, the synthesis of zeolites usually requires solvents, which often lead to water pollution, loss of silicon and aluminium components, and low synthesis efficiency. In this account, ZSM-5 zeolites were synthesized from natural clay palygorskite (PAL) by acid leaching, followed by thermal treatment under solvent-free conditions. The as-obtained ZSM-5 zeolites exhibited high crystallinity and mesoporous structure. The NMR spectra of ZSM-5 zeolites confirmed the presence of aluminium element derived from the acid-treated PAL (APAL) existed in zeolite framework. Thus, PAL was simultaneously employed as silica and aluminium sources for zeolite preparation. The Si/Al molar ratio of ZSM-5 zeolites could be adjusted by adding NaAlO 2 , but against growth of ZSM-5 zeolites, resulting in formation of analcime. On the other hand, long thermal treatment for 72 h caused the dissolution of ZSM-5 zeolite crystals and formation of analcime. Overall, calcination could enhance the activity of APAL and crystallinity of ZSM-5 zeolites, and solvent-free synthesis of zeolites from clay might efficiently reduce the cost of zeolites.

中文翻译：

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以坡缕石为原料在无溶剂条件下合成ZSM-5沸石

沸石因其众多有趣的特性而广泛应用于气体吸附和分离、催化和离子交换。然而，沸石的合成通常需要溶剂，这往往会导致水污染，硅和铝组分的损失，合成效率低。在这个帐户中，ZSM-5 沸石是由天然粘土坡缕石 (PAL) 通过酸浸合成，然后在无溶剂条件下进行热处理。所获得的 ZSM-5 沸石表现出高结晶度和介孔结构。ZSM-5 沸石的 NMR 谱证实了沸石骨架中存在源自酸处理的 PAL (APAL) 的铝元素。因此，PAL 同时用作沸石制备的二氧化硅和铝源。加入NaAlO 2 可以调节ZSM-5沸石的Si/Al摩尔比，但不利于ZSM-5沸石的生长，导致方沸石的形成。另一方面，72 小时的长时间热处理会导致 ZSM-5 沸石晶体溶解并形成方沸石。总体而言，煅烧可以提高 APAL 的活性和 ZSM-5 沸石的结晶度，从粘土中无溶剂合成沸石可能有效降低沸石的成本。