Dynamic Nuclear Polarization NMR Enables the Analysis of Sn-Beta Zeolite Prepared with Natural Abundance [superscript 119]Sn Precursors
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Gunther-2014-Dynamic nuclear.pdf
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Author(s)
Gunther, William Robert
Michaelis, Vladimir K.
Caporini, Marc A.
Griffin, Robert Guy
Roman, Yuriy
Date Issued
April 2014
Journal
Journal of the American Chemical Society
Publisher
American Chemical Society (ACS)
Citation
Gunther, William R., Vladimir K. Michaelis, Marc A. Caporini, Robert G. Griffin, and Yuriy Roman-Leshkov. “Dynamic Nuclear Polarization NMR Enables the Analysis of Sn-Beta Zeolite Prepared with Natural Abundance [superscript 119]Sn Precursors.” Journal of the American Chemical Society 136, no. 17 (April 30, 2014): 6219–6222. © 2014 American Chemical Society
Version
Final published version
Abstract
The catalytic activity of tin-containing zeolites, such as Sn-Beta, is critically dependent on the successful incorporation of the tin metal center into the zeolite framework. However, synchrotron-based techniques or solid-state nuclear magnetic resonance (ssNMR) of samples enriched with [superscript 119]Sn isotopes are the only reliable methods to verify framework incorporation. This work demonstrates, for the first time, the use of dynamic nuclear polarization (DNP) NMR for characterizing zeolites containing ~2 wt % of natural abundance Sn without the need for [superscript 119]Sn isotopic enrichment. The biradicals TOTAPOL, bTbK, bCTbK, and SPIROPOL functioned effectively as polarizing sources, and the solvent enabled proper transfer of spin polarization from the radical’s unpaired electrons to the target nuclei. Using bCTbK led to an enhancement (ε) of 75, allowing the characterization of natural-abundance [superscript 119]Sn-Beta with excellent signal-to-noise ratios in <24 h. Without DNP, no [superscript 119]Sn resonances were detected after 10 days of continuous analysis.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
Massachusetts Institute of Technology. Department of Chemistry
Francis Bitter Magnet Laboratory (Massachusetts Institute of Technology)
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DOI of Published Version
https://doi.org/10.1021/ja502113d
