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Titolo:
MOBILITY OF METHANE IN ZEOLITE NAY BETWEEN 100 AND 250 K - A QUASI-ELASTIC NEUTRON-SCATTERING STUDY
Autore:
JOBIC H; BEE M; KEARLEY GJ;
Indirizzi:
INST RECH CATALYSE,CNRS,2 AVE ALBERT EINSTEIN F-69626 VILLEURBANNE FRANCE UNIV GRENOBLE 1,SPECTROMETRIE PHYS LAB F-38402 ST MARTIN DHERES FRANCE INST MAX VON LAUE PAUL LANGEVIN F-38042 GRENOBLE 9 FRANCE
Titolo Testata:
Journal of physical chemistry
fascicolo: 17, volume: 98, anno: 1994,
pagine: 4660 - 4665
SICI:
0022-3654(1994)98:17<4660:MOMIZN>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
NUCLEAR-MAGNETIC-RESONANCE; MOLECULAR-DYNAMICS; SELF-DIFFUSION; TEMPERATURE; SIMULATION; SILICALITE; HYDROCARBONS; ENERGETICS; DEPENDENCE; MOTIONS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
30
Recensione:
Indirizzi per estratti:
Citazione:
H. Jobic et al., "MOBILITY OF METHANE IN ZEOLITE NAY BETWEEN 100 AND 250 K - A QUASI-ELASTIC NEUTRON-SCATTERING STUDY", Journal of physical chemistry, 98(17), 1994, pp. 4660-4665

Abstract

The translational and rotational dynamics of methane in NaY zeolite have been studied by quasi-elastic neutron scattering (QENS) at different temperatures and loadings. The QENS results reveal a marked temperature sensitivity. At 100 K, there is no migration of the methane from cage to cage on the 35-ps time scale of the experiment so that the time spent by a molecule in a supercage is longer than this. At 100 K, 88% of the methane molecules are found to be localized, performing rotational diffusion, and 12% of molecules diffuse in a volume limited by the walls of the supercages. At 150 K, there are no trapped molecules, 44% of methane molecules diffuse between the supercages and 56% diffuse locally within the supercages. At 200 and 250 K, the proportion of mobile molecules and their diffusion coefficients increase. The QENS results are in good agreement with theoretical methods which predict a progressive delocalization of the molecules with increasing temperature. The self-diffusion coefficients determined by QENS are in excellent agreement with the NMR results and, to a lesser extent, with moleculardynamics simulations. The activation energy for self-diffusion is of 6.3 kJ mol(-1).

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 12/08/20 alle ore 20:54:10