Clay minerals intercalated with inorganic species, known as pillared interlayered clays, have received extensive attention in recent decades. In this work, by comparison with those of Keggin-Al13, the formation processes of Keggin-Al30 are discussed based on different hydrolysis reactions. X-ray diffraction (XRD), field-emission scanning electron microscope, and thermogravimetric analyses were applied to compare differences in crystal structure, morphology, and thermal stability between Keggin-Al13 and Keggin-Al30 (sulfates). High temperature and excess monomeric Al species are key factors controlling the transformation from e-Keggin-Al13 to δ-Keggin-Al13 and finally to Keggin-Al30. A decrease of the crystal symmetry from Keggin-Al13 to Keggin-Al30 was confirmed by shifts of reflections (and decreases of intensities) on XRD patterns. Keggin-Al30 has a more compact structure, which leads to higher thermal stability. The distributions of functional groups and positive charges on the surface of Keggin-Al30 result in a “lying flat” arrangement configuration in the interlayer region of montmorillonite. Exploring the behaviors of polycations as intercalants from their formation, transformation, and properties during the pillaring process may offer better understandings of the enhanced properties and wide applications of pillared interlayered clays.

中文翻译：

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Keggin-Al30：Keggin-Al30 柱撑蒙脱石的插层剂

近几十年来，夹有无机物种的粘土矿物，被称为柱状夹层粘土，受到了广泛的关注。在这项工作中，通过与 Keggin-Al13 的比较，基于不同的水解反应讨论了 Keggin-Al30 的形成过程。应用 X 射线衍射 (XRD)、场发射扫描电子显微镜和热重分析来比较 Keggin-Al13 和 Keggin-Al30（硫酸盐）在晶体结构、形态和热稳定性方面的差异。高温和过量的单体 Al 物种是控制从 e-Keggin-Al13 到 δ-Keggin-Al13 并最终转化为 Keggin-Al30 的关键因素。从 Keggin-Al13 到 Keggin-Al30 的晶体对称性降低通过 XRD 图案上的反射变化（和强度降低）得到证实。Keggin-Al30 具有更紧凑的结构，从而具有更高的热稳定性。Keggin-Al30 表面的官能团和正电荷的分布导致蒙脱石层间区域的“平躺”排列配置。探索聚阳离子作为嵌入剂在柱撑过程中的形成、转化和性能的行为，可以更好地理解柱撑夹层粘土的增强性能和广泛应用。