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Mobility of tert-Butyl Alcohol in MFI Framework Type Studied by Deuterium NMR Научная публикация

Журнал The Journal of Physical Chemistry C
ISSN: 1932-7447 , E-ISSN: 1932-7455
Вых. Данные Год: 2012, Том: 116, Номер: 16, Страницы: 8956-8963 Страниц : 8 DOI: 10.1021/jp212042m
Ключевые слова Activation energy; Alcohols; Deuterium; Diffusion barriers; Functional groups; Hydrogen bonds; Silicate minerals; Spheres; Tools
Авторы Nishchenko Alena M. 1 , Kolokolov Daniil I. 2 , Gabrienko Anton A. 2 , Stepanov Alexander G. 2
Организации
1 Faculty of Physics, Department of Chemical and Biological Physics, Novosibirsk State University, Pirogova Street 2, Novosibirsk 630090, Russia
2 Boreskov Institute of Catalysis, Siberian Branch of Russian Academy of Sciences, Prospekt Akademika Lavrentieva 5, Novosibirsk 630090, Russia

Информация о финансировании (1)

1 Российский фонд фундаментальных исследований 12-03-00316

Реферат: The molecular mobility of deuterated tert-butyl alcohol (TBA) adsorbed in MFI framework type (silicalite-1 andZSM-5 zeolite) has been studied by use of 2H NMR spectroscopy in the range of 106−453 K. In H-ZSM-5, the reorientation of the molecule as a whole is strongly restricted (τC≪ Q0−1 ≈ 10−6 s) by hydrogen bonding to Brønsted acid sites(BAS). Being adsorbed to BAS, the motion of TBA molecules is described by intramolecular rotations around two successive C3 and C3′ axes (CD3−C and C−O bonds). The activation energy for the methyl groups rotation around the C−O bond (Ea = 8.0± 1.6 kJ mol−1) is two times lower compared to that in solid TBA (J. Phys. Chem. A 2011, 115, 7428). This shows that the motion of the butyl fragment of TBA in MFI framework is less restricted compared to the case of solid TBA. In silicalite-1, the TBA molecule is additionally involved into reorientational motions as a whole: one of the motions represents an exchange among orientations provided by the directions of four framework channels driven by the translational jump diffusion. The activation barriers for the jump diffusion between two zigzag channels (Ea = 7 ± 2 kJ mol−1) and between zigzag and straight channels (Ea =5 ± 1 kJ mol−1) are of the similar values. The other motion represents a large-amplitude wobbling of the TBA molecule localized at a channel intersection site cavity. This motion is described by a fast restricted wobbling of the molecular axis in a sphere sector.The wobbling boundaries become gradually broader as temperature increases, allowing thus a larger accessible space for the TBA molecule to explore. The anisotropy of this motion persists even at 453 K, revealing the presence of a strong intracavity barrier that blocks the TBA from free rotational diffusion inside the cavity. This study demonstrates that the 2H NMR analysis of both line shape and spin−lattice relaxation represents a powerful tool to investigate the particular pore confinement effect on the molecular mobility of TBA adsorbed in the MFI framework.
Библиографическая ссылка: Nishchenko A.M. , Kolokolov D.I. , Gabrienko A.A. , Stepanov A.G.
Mobility of tert-Butyl Alcohol in MFI Framework Type Studied by Deuterium NMR
The Journal of Physical Chemistry C. 2012. V.116. N16. P.8956-8963. DOI: 10.1021/jp212042m WOS Scopus РИНЦ CAPlusCA OpenAlex
Даты:
Поступила в редакцию: 14 дек. 2011 г.
Принята к публикации: 3 апр. 2012 г.
Опубликована online: 15 апр. 2012 г.
Опубликована в печати: 26 апр. 2012 г.
Идентификаторы БД:
Web of science: WOS:000303173900014
Scopus: 2-s2.0-84860365587
РИНЦ: 17983907
Chemical Abstracts: 2012:508682
Chemical Abstracts (print): 156:516897
OpenAlex: W2313355141
Цитирование в БД:
БД Цитирований
Web of science 16
Scopus 17
РИНЦ 17
OpenAlex 18
Альметрики: