Zeolites are crystalline microporous aluminosilicates of paramount importance. The siting of cations balancing the negative charge of framework Al affects the catalytic and sorption properties of cation-exchanged zeolites. The siting of Na⁺ cations in dehydrated Si-rich ferrierite zeolites is investigated by ²³Na (ultra)-high-field (MQ)MAS NMR spectroscopy together with DFT to obtain the Na⁺ siting and the local structure of nine Na⁺ cationic sites formed by two 6-rings and two 8-rings having one Al atom located in different framework T sites. The occupation of the Na⁺ cationic sites is not controlled by their relative energies but by the kinetics of the Na⁺ ion-exchange. ²³Na solid-state NMR spectroscopy alone can determine the ring forming the Na⁺ site but not which T site is occupied by Al in that ring. The developed methodology represents a highly promising tool for the analysis of the Na⁺ arrangements in zeolites and other crystalline matrices.

中文翻译：

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无机基质中单价阳离子的 NMR 晶体学：镁碱沸石中 Na+ 位点和 Na+ 位点的局部结构

沸石是极其重要的结晶微孔硅铝酸盐。平衡骨架Al负电荷的阳离子位置影响阳离子交换沸石的催化和吸附性能。采用²³ Na(超)-高场(MQ)MAS核磁共振波谱结合DFT研究脱水富硅镁碱沸石中Na ^{+阳离子的位点，得到Na +}位点和9个Na ⁺阳离子位点的局部结构由两个 6 环和两个 8 环组成，其中一个 Al 原子位于不同的骨架 T 位点。^{Na +}阳离子位点的占据不是由它们的相对能量控制，而是由 Na ⁺离子交换的动力学控制。²³ Na 固态 NMR 光谱单独可以确定形成 Na ⁺位点的环，但不能确定该环中的哪个 T 位点被 Al 占据。所开发的方法代表了一种非常有前途的工具，用于分析沸石和其他晶体基质中的 Na ⁺排列。