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Influence of Cation Exchange on the ²⁷Al-NMR Spectra of Zeolites

Masierak, W. ; Emmler, T. ; Buntkowsky, Gerd ; Gutsze, A. (2021):
Influence of Cation Exchange on the ²⁷Al-NMR Spectra of Zeolites. (Publisher's Version)
In: Zeitschrift für Physikalische Chemie, 217 (12), pp. 1613-1626. De Gruyter, ISSN 0942-9352, e-ISSN 2196-7156,
DOI: 10.26083/tuprints-00019693,
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Item Type: Article
Origin: Secondary publication service
Status: Publisher's Version
Title: Influence of Cation Exchange on the ²⁷Al-NMR Spectra of Zeolites
Language: English
Abstract:

The influence of cation exchange on the ²⁷Al-NMR spectra of NaA-zeolites has been studied by ²⁷Al-MAS- and MQ-MAS-Solid State-NMR. From the ²⁷Al-spectra a characterization of the different Al sites in the A zeolites according to their chemical environment and the structural changes on the aluminosilicate network caused by the cation exchange are obtained. It is found that the exchange with cations with smaller ion-radius cause stronger distortions of the ²⁷Al-NMR-spectra than exchange with larger cations like Ba²⁺. Employing MQ-MAS spectroscopy these distortions are revealed as second order quadrupolar effects for the smaller cations and as a combination of chemical shift and second order quadrupolar interaction for the Ba cation. These changes of the quadrupolar coupling are interpreted numerically via calculations of the lowering of the symmetry of the EFG tensor. Finally it is found that the exchange with divalent cations leads to distortions of the zeolitic framework and the formation of an extra-framework aluminum. To the best of our knowledge this is for the first time that evidence for the production of extra frame work aluminum by pure cation exchange without any thermal treatment has been found in type A zeolites.

Journal or Publication Title: Zeitschrift für Physikalische Chemie
Journal volume: 217
Number: 12
Publisher: De Gruyter
Classification DDC: 500 Naturwissenschaften und Mathematik > 540 Chemie
Divisions: 07 Department of Chemistry > Physical Chemistry
Date Deposited: 01 Oct 2021 11:35
Last Modified: 01 Oct 2021 11:35
DOI: 10.26083/tuprints-00019693
Corresponding Links:
URN: urn:nbn:de:tuda-tuprints-196938
Additional Information:

Keywords: NaA-Zeolite / ²⁷Al-MAS-NMR / Quadrupol Coupling Constants

URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/19693
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