Molecular Dynamics of iso-Butyl Alcohol Inside Zeolite H-ZSM-5 as Studied by Deuterium Solid-State NMR Spectroscopy Full article
| Journal |
The Journal of Physical Chemistry B
ISSN: 1520-6106 , E-ISSN: 1520-5207 |
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| Output data | Year: 2000, Volume: 104, Number: 32, Pages: 7677-7685 Pages count : 9 DOI: 10.1021/jp000581e | ||||
| Tags | NUCLEAR MAGNETIC-RESONANCE; X-TYPE ZEOLITES; H-2 NMR; ISOBUTYL ALCOHOL; CATALYTIC DEHYDRATION; ETHENE MOLECULES; C-13 CP/MAS; P-XYLENE; N-HEXANE; BENZENE | ||||
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Funding (1)
| 1 | International Association for the Promotion of Co-operation with Scientists from the New Independent States of the Former Soviet Union | 96-1177 |
Abstract:
The molecular mobility of iso-butyl alcohol, selectively deuterated in the methylene group (iBA[1-d2]) or in the methyl groups (iBA[3-d6]), adsorbed on zeolite H-ZSM-5 was studied with 2H NMR spectroscopy. At 115−293 K, the 2H NMR line shape for the adsorbed iBA[3-d6] represents a superposition of one solidlike and two liquidlike signals, whereas for iBA[1-d2], it is a superposition of the solidlike and the liquidlike lines. Two liquidlike signals are assigned to the alcohol molecules isotropically reorienting with correlation time τR ∼ 1 × 10-6 s by jumping among Al−OH−Si groups, which are located inside the channels and at channel intersections of the zeolite channel system. Being adsorbed on Al−OH−Si groups, these two types of alcohol molecules differ in the effective amplitude of libration γ0 (γ0 is a libration cone semiangle) of the methyl groups, which is large for both adsorption sites (γ0 ∼ 52° for one of the types, and γ0 ∼ 72° for the other). The solidlike signal with the observed quadrupole splitting of 38 kHz is assigned to the alcohol molecules located inside the zeolite channels. These alcohol molecules reorient with a correlation time τR > 4.2 × 10-6 s, and their methyl groups experience small librations with amplitude γ0 ∼ 19°. Methyl groups of the alcohol molecules located at channel intersections rotate about the CH3−CH axis with correlation time τP = (1.4−2.6) × 10-11 s at 293 K and activation energy EP = 11−12 kJ/mol, whereas those located inside the channel rotate with correlation time τj ∼ 2 × 10-10 s at 293 K and activation energy Ej = 10.5 kJ/mol. The difference in the rotation rates is attributed to the influence of the walls of the zeolite channel on dynamics of one-axis methyl group rotation, which is expected to be more profound in the confined area of a narrow channel than at channel intersections.
Cite:
Stepanov A.G.
, Alkaev M.M.
, Shubin A.A.
Molecular Dynamics of iso-Butyl Alcohol Inside Zeolite H-ZSM-5 as Studied by Deuterium Solid-State NMR Spectroscopy
The Journal of Physical Chemistry B. 2000. V.104. N32. P.7677-7685. DOI: 10.1021/jp000581e WOS Scopus РИНЦ ANCAN OpenAlex
Molecular Dynamics of iso-Butyl Alcohol Inside Zeolite H-ZSM-5 as Studied by Deuterium Solid-State NMR Spectroscopy
The Journal of Physical Chemistry B. 2000. V.104. N32. P.7677-7685. DOI: 10.1021/jp000581e WOS Scopus РИНЦ ANCAN OpenAlex
Dates:
| Submitted: | Feb 14, 2000 |
| Accepted: | May 18, 2000 |
| Published online: | Jul 25, 2000 |
| Published print: | Aug 1, 2000 |
Identifiers:
| Web of science: | WOS:000088828900017 |
| Scopus: | 2-s2.0-0034248731 |
| Elibrary: | 41806145 |
| Chemical Abstracts: | 2000:500215 |
| Chemical Abstracts (print): | 133:135010 |
| OpenAlex: | W2076717925 |