Synthesis, Isotopic Enrichment, and Solid-State NMR Characterization of Zeolites Derived from the Assembly, Disassembly, Organization, Reassembly Process.
Synthesis, Isotopic Enrichment, and Solid-State NMR Characterization of Zeolites Derived from the Assembly, Disassembly, Organization, Reassembly Process.
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DOI：
10.1021/jacs.7b00386
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发表时间：
2017-04-12
影响因子：
15
通讯作者：
Ashbrook SE
中科院分区：
文献类型：
--
作者：
Bignami GPM;Dawson DM;Seymour VR;Wheatley PS;Morris RE;Ashbrook SE
沸石在工业催化和医学等多种领域的巨大效用和重要性，促使人们对具有新特性和应用的新框架类型的能力产生了相当大的兴趣。最近推出的非常规组装、拆卸、组织、重组（ADOR）方法代表了一种令人兴奋的新方法，通过选择性地拆卸预先制备的水解不稳定框架，然后重新组装得到的产物，形成具有新拓扑结构的材料，从而获得具有目标结构的固体。然而，这种强大的合成方法背后的水解机制尚不清楚，需要进一步研究不同条件下的动力学行为和反应结果。在这项工作中，我们报告了通过合成富集29si的起始Ge-UTL框架，并在水解过程中从富集17O的水中掺入17O，对17O-和双富集17O和29si的utl衍生沸石进行了优化的ADOR合成和随后的固态表征。17O和29Si核磁共振实验能够证明水解和重排过程发生在比衍射所看到的更长的时间尺度上。在大量沸石层中出人意料地观察到高水平的17O，而不仅仅局限于层间间距，揭示了比以前认为的更广泛的水解重排。这项工作揭示了水在ADOR过程中所起的作用，并提供了对所涉及的结构变化的详细机制的见解。
The great utility and importance of zeolites in fields as diverse as industrial catalysis and medicine has driven considerable interest in the ability to target new framework types with novel properties and applications. The recently introduced and unconventional assembly, disassembly, organization, reassembly (ADOR) method represents one exciting new approach to obtain solids with targeted structures by selectively disassembling preprepared hydrolytically unstable frameworks and then reassembling the resulting products to form materials with new topologies. However, the hydrolytic mechanisms underlying such a powerful synthetic method are not understood in detail, requiring further investigation of the kinetic behavior and the outcome of reactions under differing conditions. In this work, we report the optimized ADOR synthesis, and subsequent solid-state characterization, of 17O- and doubly 17O- and 29Si-enriched UTL-derived zeolites, by synthesis of 29Si-enriched starting Ge-UTL frameworks and incorporation of 17O from 17O-enriched water during hydrolysis. 17O and 29Si NMR experiments are able to demonstrate that the hydrolysis and rearrangement process occurs over a much longer time scale than seen by diffraction. The observation of unexpectedly high levels of 17O in the bulk zeolitic layers, rather than being confined only to the interlayer spacing, reveals a much more extensive hydrolytic rearrangement than previously thought. This work sheds new light on the role played by water in the ADOR process and provides insight into the detailed mechanism of the structural changes involved.