書誌事項
- 公開日
- 2016-12-15
- 権利情報
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- https://creativecommons.org/licenses/by/4.0
- https://creativecommons.org/licenses/by/4.0
- DOI
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- 10.1038/ncomms13820
- 公開者
- Springer Science and Business Media LLC
説明
<jats:title>Abstract</jats:title><jats:p>Zeolites and amorphous silica-alumina (ASA), which both provide Brønsted acid sites (BASs), are the most extensively used solid acid catalysts in the chemical industry. It is widely believed that BASs consist only of tetra-coordinated aluminum sites (Al<jats:sup>IV</jats:sup>) with bridging OH groups in zeolites or nearby silanols on ASA surfaces. Here we report the direct observation in ASA of a new type of BAS based on penta-coordinated aluminum species (Al<jats:sup>V</jats:sup>) by <jats:sup>27</jats:sup>Al-{<jats:sup>1</jats:sup>H} dipolar-mediated correlation two-dimensional NMR experiments at high magnetic field under magic-angle spinning. Both BAS-Al<jats:sup>IV</jats:sup> and -Al<jats:sup>V</jats:sup> show a similar acidity to protonate probe molecular ammonia. The quantitative evaluation of <jats:sup>1</jats:sup>H and <jats:sup>27</jats:sup>Al sites demonstrates that BAS-Al<jats:sup>V</jats:sup> co-exists with BAS-Al<jats:sup>IV</jats:sup> rather than replaces it, which opens new avenues for strongly enhancing the acidity of these popular solid acids.</jats:p>
収録刊行物
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- Nature Communications
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Nature Communications 7 (1), 2016-12-15
Springer Science and Business Media LLC