Structure of framework aluminum Lewis sites and perturbed aluminum atoms in zeolites as determined by 27Al{1H} REDOR (3Q) MAS NMR spectroscopy and DFT/molecular mechanics

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388955%3A_____%2F15%3A00439638" target="_blank" >RIV/61388955:_____/15:00439638 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/61389013:_____/15:00439638

Výsledek na webu

<a href="http://dx.doi.org/10.1002/anie.201409635" target="_blank" >http://dx.doi.org/10.1002/anie.201409635</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1002/anie.201409635" target="_blank" >10.1002/anie.201409635</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Structure of framework aluminum Lewis sites and perturbed aluminum atoms in zeolites as determined by 27Al{1H} REDOR (3Q) MAS NMR spectroscopy and DFT/molecular mechanics

Popis výsledku v původním jazyce

Zeolites are highly important heterogeneous catalysts. Besides Br?nsted SiOHAl acid sites, also framework AlFR Lewis acid sites are often found in their H-forms. The formation of AlFR Lewis sites in zeolites is a key issue regarding their selectivity inacid-catalyzed reactions. The local structures of AlFR Lewis sites in dehydrated zeolites and their precursors??perturbed AlFR atoms in hydrated zeolites?were studied by high-resolution MAS NMR and FTIR spectroscopy and DFT/MM calculations. Perturbed framework Al atoms correspond to (SiO)3AlOH groups and are characterized by a broad 27Al NMR resonance (?i=59?62?ppm, CQ=5?MHz, and ?=0.3?0.4) with a shoulder at 40?ppm in the 27Al?MAS?NMR spectrum. Dehydroxylation of (SiO)3AlOH occurs at mild temperaturesand leads to the formation of AlFR Lewis sites tricoordinated to the zeolite framework. Al atoms of these (SiO)3Al Lewis sites exhibit an extremely broad 27Al?NMR resonance (?i67?ppm, CQ20?MHz, and ?0.1).

Název v anglickém jazyce

Structure of framework aluminum Lewis sites and perturbed aluminum atoms in zeolites as determined by 27Al{1H} REDOR (3Q) MAS NMR spectroscopy and DFT/molecular mechanics

Popis výsledku anglicky

Zeolites are highly important heterogeneous catalysts. Besides Br?nsted SiOHAl acid sites, also framework AlFR Lewis acid sites are often found in their H-forms. The formation of AlFR Lewis sites in zeolites is a key issue regarding their selectivity inacid-catalyzed reactions. The local structures of AlFR Lewis sites in dehydrated zeolites and their precursors??perturbed AlFR atoms in hydrated zeolites?were studied by high-resolution MAS NMR and FTIR spectroscopy and DFT/MM calculations. Perturbed framework Al atoms correspond to (SiO)3AlOH groups and are characterized by a broad 27Al NMR resonance (?i=59?62?ppm, CQ=5?MHz, and ?=0.3?0.4) with a shoulder at 40?ppm in the 27Al?MAS?NMR spectrum. Dehydroxylation of (SiO)3AlOH occurs at mild temperaturesand leads to the formation of AlFR Lewis sites tricoordinated to the zeolite framework. Al atoms of these (SiO)3Al Lewis sites exhibit an extremely broad 27Al?NMR resonance (?i67?ppm, CQ20?MHz, and ?0.1).

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

CI - Průmyslová chemie a chemické inženýrství

OECD FORD obor

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Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2015

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Angewandte Chemie - International Edition

ISSN

1433-7851

e-ISSN

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Svazek periodika

54

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

DE - Spolková republika Německo

Počet stran výsledku

5

Strana od-do

541-545

Kód UT WoS článku

000347238800026

EID výsledku v databázi Scopus

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