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Effect of Al/Si Substitutions and Silanol Nests on the Local Geometry of Si and Al Framework Sites in Silicone-Rich Zeolites: A Combined High Resolution Al-27 and Si-29 NMR and Density Functional Theory/Molecular Mechanics Study
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SYSNO ASEP 0336493 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Effect of Al/Si Substitutions and Silanol Nests on the Local Geometry of Si and Al Framework Sites in Silicone-Rich Zeolites: A Combined High Resolution Al-27 and Si-29 NMR and Density Functional Theory/Molecular Mechanics Study Title Efekt Al/Si substituce a silanolových hnízd na lokální geometrii Si a Al skeletálních míst v křemíkem bohatých zeolitech: kombinovaná studie využívající vysoko rozlišenou 27Al a 29Si NMR spektroskopii a DFT/molekulovou mechaniku Author(s) Dědeček, Jiří (UFCH-W) RID, ORCID
Sklenák, Štěpán (UFCH-W) RID, ORCID, SAI
Li, Chengbin (UFCH-W)
Gao, Fei (UFCH-W)
Brus, Jiří (UMCH-V) RID, ORCID
Zhu, Q. (JP)
Tatsumi, T. (JP)Source Title Journal of Physical Chemistry C. - : American Chemical Society - ISSN 1932-7447
Roč. 113, č. 32 (2009), s. 14454-14466Number of pages 13 s. Language eng - English Country US - United States Keywords ab-initio calculation ; NMR spectroscopy ; DFT/MM Subject RIV CF - Physical ; Theoretical Chemistry R&D Projects IAA400400812 GA AV ČR - Academy of Sciences of the Czech Republic (AV ČR) IAA400400908 GA AV ČR - Academy of Sciences of the Czech Republic (AV ČR) IAA400400904 GA AV ČR - Academy of Sciences of the Czech Republic (AV ČR) GA203/09/1627 GA ČR - Czech Science Foundation (CSF) KAN100400702 GA AV ČR - Academy of Sciences of the Czech Republic (AV ČR) CEZ AV0Z40400503 - UFCH-W (2005-2011) AV0Z40500505 - UMCH-V (2005-2011) UT WOS 000268661300059 DOI 10.1021/jp9042232 Annotation We employed Si-29 and Al-27 (3Q) magic-angle spinning (MAS) NMR spectroscopy and density functional theory/molecular mechanics (DFT/MM) calculations to investigate the effect of Al/Si substitutions and the presence of silanol nests on the Si-29 and Al-27 NMR parameters as well as the local geometry Of SiO4 and AlO4- tetrahedra of the nearest and next-nearest neighboring Si and Al atoms. The silicon-rich zeolite of the chabazite structure (Si/Al 38) was chosen for this study as a representative model of silicon-rich zeolites since it exhibits a low number of distinguishable T sites. Our computational results show the following: (1) Al atoms can occupy three different crystallographic T sites in the framework of chabazite (Si/Al 38). This result is in agreement with two observed Al-27 NMR resonances. (II) An Al/Si substitution causes a downshift of the Si-29 chemical shift of the nearest neighboring Si atoms (Al-O-Si) by 4-11 ppm... Workplace J. Heyrovsky Institute of Physical Chemistry Contact Michaela Knapová, michaela.knapova@jh-inst.cas.cz, Tel.: 266 053 196 Year of Publishing 2010
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