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Titolo:
Effect of the surface energy barrier on sorbate diffusion in AlPO4-5
Autore:
Arya, G; Maginn, EJ; Chang, HC;
Indirizzi:
Univ Notre Dame, Dept Chem Engn, Notre Dame, IN 46556 USA Univ Notre DameNotre Dame IN USA 46556 em Engn, Notre Dame, IN 46556 USA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 14, volume: 105, anno: 2001,
pagine: 2725 - 2735
SICI:
1520-6106(20010412)105:14<2725:EOTSEB>2.0.ZU;2-9
Fonte:
ISI
Lingua:
ENG
Soggetto:
SELF-DIFFUSION; MOLECULAR SIMULATION; SILICALITE; ZEOLITES; DYNAMICS; METHANE; ADSORPTION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
24
Recensione:
Indirizzi per estratti:
Indirizzo: Maginn, EJ Univ Notre Dame, Dept Chem Engn, Notre Dame, IN 46556 USA Univ Notre Dame Notre Dame IN USA 46556 tre Dame, IN 46556 USA
Citazione:
G. Arya et al., "Effect of the surface energy barrier on sorbate diffusion in AlPO4-5", J PHYS CH B, 105(14), 2001, pp. 2725-2735

Abstract

The importance of pore exit effects on the diffusion of molecules in AlPO4-5 pores is evaluated using two molecular modeling techniques. In the firstapproach, a dual control volume grand canonical molecular dynamics technique is used to obtain molecular fluxes of methane out of the truncated crystal as a function of temperature and sorbate loading. The simulation resultsindicate the presence of a low-temperature surface barrier for diffusion, which retards the flux of methane relative to its apparent flux in the intracrystalline regions of the material. This pore exit barrier tends to diminish as temperature and loading increase. An explanation based on clusteringphenomena is proposed to explain the latter. Next, a simple activated transport model is proposed to predict the relative importance of the surface barrier on the transport of sorbates in AlPO4-5. The potential of mean forcefor a single sorbate molecule along the pore axis of a truncated crystal provides the required activation energy barriers for the model. The model correctly predicts the reduction in the importance of exit effects with an increase in the temperature. It is also observed that exit effects become more important as the ratio of the size of the sorbate molecule to the pore size approaches unity. In particular, exit effects are significant in micrometer-thick AlPO4-5 crystals in the case of large molecules such as SnBr4 andCCl4 at room temperature.

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Documento generato il 05/07/20 alle ore 07:31:41