The formation and evolution of building units for zeolites play an important role during crystallization. Interzeolite transformation offers a better platform for investigating the conversion behaviors of such building units and the specific crystallization mechanism of zeolites. Herein, we show the different evolution of double six-membered rings (D6R) during the interzeolite transformation from FAU, MFI and *BEA into AEI zeolites based on UV Raman spectroscopy in combination with X-ray powder diffraction (XRD) and DFT calculations. It is found that a direct transfer of D6R occurs from the FAU into AEI zeolite since they share the same structural units (D6R), while towards the newly expanded synthetic strategy from pentasil-type zeolites MFI and *BEA into AEI zeolites, the formation of D6R units in the AEI framework results from the reassembly of single four-membered rings (S4R) and single six-membered rings (S6R) generated by breaking a large number of single five-membered rings (S5R) that are very fragile and easy to decompose under hydrothermal transformation conditions. Such results provide a clear and direct spectroscopic characterization at the molecular level, which will be of great significance in accomplishing a deep understanding of the interzeolite transformation mechanism.

中文翻译：

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从FAU，MFI或* BEA到AEI的沸石间转变中D6R单元的演变：转移还是重组？

沸石结构单元的形成和演化在结晶过程中起重要作用。沸石间的转化为研究此类建筑单元的转化行为和特定的结晶机理提供了一个更好的平台。在本文中，我们基于UV拉曼光谱结合X射线粉末衍射（XRD）和DFT计算，显示了从FAU，MFI和* BEA到FEI，MFI和* BEA的沸石间转变过程中双六元环（D6R）的不同演化。发现D6R直接从FAU转移到AEI沸石中，因为它们具有相同的结构单元（D6R），而正朝着从戊二醇型沸石MFI和* BEA到AEI沸石的新扩展合成策略发展，AEI框架中D6R单元的形成是由于单个四元环（S4R）和单个六元环（S6R）的重组而产生的，这些断裂是通过破坏大量非常脆弱的单个五元环（S5R）生成的并且在水热转化条件下易于分解。这样的结果在分子水平上提供了清晰，直接的光谱表征，这对于完成对沸石间转化机理的深入了解将具有重要意义。