Direct Observation of Tin in Different T-Sites of Sn-BEA by One- and Two-Dimensional 119Sn MAS NMR Spectroscopy

Yury G Kolyagin; Alexander V Yakimov; Søren Tolborg; Peter N R Vennestrøm; Irina I Ivanova

doi:10.1021/acs.jpclett.8b01415

Direct Observation of Tin in Different T-Sites of Sn-BEA by One- and Two-Dimensional ¹¹⁹Sn MAS NMR Spectroscopy

J Phys Chem Lett. 2018 Jul 5;9(13):3738-3743. doi: 10.1021/acs.jpclett.8b01415. Epub 2018 Jun 26.

Authors

Yury G Kolyagin^{1

2}, Alexander V Yakimov¹, Søren Tolborg³, Peter N R Vennestrøm^{3

4}, Irina I Ivanova^{1

2}

Affiliations

¹ Department of Chemistry , Lomonosov Moscow State University , Leninskie gory 1 , 119234 Moscow , Russia.
² A.V. Topchiev Institute of Petrochemical Synthesis RAS , 119992 Moscow , Russia.
³ Haldor Topsøe A/S , Haldor Topsøes Allé 1 , DK-2800 Kgs. Lyngby , Denmark.
⁴ Umicore Denmark ApS , Nøjsomhedsvej 20 , DK-2800 Kgs. Lyngby , Denmark.

PMID: 29874083
DOI: 10.1021/acs.jpclett.8b01415

Abstract

The direct and quantitative identification of active sites is crucial for the development of zeolite catalysts and their implementation in industry. Herein we report on the application of one-dimensional ¹¹⁹Sn direct polarization (DP) and rotational echo double-resonance (REDOR) and two-dimensional ¹¹⁹Sn magic-angle tuning (MAT) NMR spectroscopy for the identification of different Sn sites in fully dehydrated Sn-BEA zeolite. It is demonstrated that ¹¹⁹Sn magic-angle spinning (MAS) NMR techniques, modified by Carr-Purcell-Meiboom-Gill (CPMG) echo-train acquisition allow to resolve three groups of NMR signals, which can be attributed to three groups of nonequivalent T-sites based on the existing theoretical predictions: (I) T9, T4, and T3; (II) T2, T1, and T8; and (III) T7, T5, and T6. Results suggest that the sites attributed to group III are the most populated in Sn-BEA samples obtained via the fluoride route. The attribution of NMR lines to different T-sites in the structure of BEA allows for the establishment of structure-reactivity relationship and therefore for further improvement of Sn-BEA catalysts.