Zeolites are usually synthesized by hydrothermal reactions using monomeric or polymeric Al- and Si-containing precursors, whereas simple and direct routes for the rational synthesis of zeolites remain elusive. In this work, we demonstrate the synthesis of the two zeolites L (LTL type) and W (MER type) from a single molecular precursor (MP), (PyH)[Al{Ph₂Si(OSiPh₂O)₂}₂] (AlSi₆; PyH = pyridinium cation), under hydrothermal conditions using KOH as the only additive. Under acidic conditions, the heptanuclear structure of AlSi₆ is hydrolyzed without cleavage of the Si–Ph bonds, while the hydrothermal reaction under basic conditions allows the crystallization of zeolites under concomitant Si–Ph cleavage. X-ray diffraction and scanning electron microscopy studies revealed that zeolite L, which exhibits a cylindrical morphology, was produced selectively by hydrothermal treatment of AlSi₆ at 160–200 °C in the presence of KOH (3 eq.). In contrast, increasing the amount of KOH (from 6 to 12 eq.) resulted in the formation of zeolite W with a twin-ball morphology. The specific surface area and Si/Al ratios of the synthesized zeolites L and W are comparable to those previously reported. These experimental results suggest promising potential of structurally and compositionally well-defined MPs, including even those with organic functional groups, for the construction of zeolites.

中文翻译：

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从单一来源的七核铝硅酸盐前驱物轻松选择性地合成L和W沸石

沸石通常是使用单体或聚合的含Al和Si的前体通过水热反应合成的，而合理合成沸石的简单直接途径仍然难以捉摸。在这项工作中，我们演示了从单个分子前体（MP）（PyH）[Al {Ph ₂ Si（OSiPh ₂ O）₂ } ₂ ]合成两种L（LTL型）和W（MER型）沸石的方法。（AlSi ₆； PyH =吡啶鎓阳离子），在水热条件下使用KOH作为唯一添加剂。在酸性条件下，AlSi ₆的七核结构水解时没有Si-Ph键断裂，而在基本条件下的水热反应可使沸石在伴随的Si-Ph断裂时结晶。X射线衍射和扫描电子显微镜研究表明，通过对AlSi ₆进行水热处理，选择性地产生了呈圆柱形形态的沸石L。在KOH（3当量）存在的条件下于160–200°C。相反，增加KOH的量（从6当量至12当量）导致形成具有双球形态的沸石W。合成的沸石L和W的比表面积和Si / Al比与先前报道的相当。这些实验结果表明，结构上和组成上明确的MP（包括那些具有有机官能团的MP）在构造沸石方面具有广阔的前景。