Formation and local structure of framework Al Lewis sites in beta zeolites

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388955%3A_____%2F22%3A00555736" target="_blank" >RIV/61388955:_____/22:00555736 - isvavai.cz</a>
Alternative codes found
RIV/61389013:_____/22:00555736
Result on the web
<a href="https://aip.scitation.org/doi/10.1063/5.0083666" target="_blank" >https://aip.scitation.org/doi/10.1063/5.0083666</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1063/5.0083666" target="_blank" >10.1063/5.0083666</a>

Result language
angličtina
Original language name
Formation and local structure of framework Al Lewis sites in beta zeolites
Original language description
Framework AlFR Lewis sites represent a substantial portion of active sites in H-BEA zeolite catalysts activated at low temperatures. We studied their nature by 27Al WURST-QCPMG nuclear magnetic resonance (NMR) and proposed a plausible mechanism of their formation based on periodic density functional theory calculations constrained by 1H MAS, 27Al WURST-QCPMG, and 29Si MAS NMR experiments and FTIR measurements. Our results show that the electron-pair acceptor of AlFR Lewis sites corresponds to an AlTRI atom tricoordinated to the zeolite framework, which adsorbs a water molecule. This AlTRI–OH2 complex is reflected in 27Al NMR resonance with δiso = 70 ± 5 ppm and CQ = 13 ± 2 MHz. In addition, the AlTRI atom with adsorbed acetonitrile-d3 (the probe of AlFR Lewis sites in FTIR spectroscopy) exhibits a similar 27Al NMR resonance. We suggest that these AlFR Lewis sites are formed from Al–OH–Si–O–Si–O–Si–OH–Al sequences located in 12-rings (i.e., close unpaired Al atoms).
Czech name
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Czech description
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Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
—
OECD FORD branch
10403 - Physical chemistry

Project
<a href="/en/project/GA19-05259S" target="_blank" >GA19-05259S: Combining advanced ultra-wideline ssNMR spectroscopy with XRPD and Computational Chemistry to study organo-metallic and frameworks materials</a><br>
Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year
2022
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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