Mesoscopic simulations of the diffusivity of ethane in beds of NaX zeolite crystals: Comparison with pulsed field gradient NMR measurements

Papadopoulos, GK; Theodorou, DN; Vasenkov, S; Karger, J

dc.contributor.author	Papadopoulos, GK	en
dc.contributor.author	Theodorou, DN	en
dc.contributor.author	Vasenkov, S	en
dc.contributor.author	Karger, J	en
dc.date.accessioned	2014-03-01T01:26:37Z
dc.date.available	2014-03-01T01:26:37Z
dc.date.issued	2007	en
dc.identifier.issn	0021-9606	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/18157
dc.subject.classification	Physics, Atomic, Molecular & Chemical	en
dc.subject.other	Digital representation	en
dc.subject.other	Knudsen regimes	en
dc.subject.other	Knudsen tortuosity	en
dc.subject.other	Crystals	en
dc.subject.other	Diffusion	en
dc.subject.other	Molecular mechanics	en
dc.subject.other	Monte Carlo methods	en
dc.subject.other	Nuclear magnetic resonance	en
dc.subject.other	Statistical methods	en
dc.subject.other	Zeolites	en
dc.subject.other	Ethane	en
dc.title	Mesoscopic simulations of the diffusivity of ethane in beds of NaX zeolite crystals: Comparison with pulsed field gradient NMR measurements	en
heal.type	journalArticle	en
heal.identifier.primary	10.1063/1.2567129	en
heal.identifier.secondary	http://dx.doi.org/10.1063/1.2567129	en
heal.identifier.secondary	094702	en
heal.language	English	en
heal.publicationDate	2007	en
heal.abstract	Mesoscopic kinetic Monte Carlo simulations and pulsed field gradient nuclear magnetic resonance (PFG NMR) measurements are compared in order to investigate the transport of ethane in a bed of NaX crystals. A novel molecular mechanics particle-based reconstruction method is employed for the digital representation of the bed, enabling for the first time a parallel study of the real system and of a computer model tailored to reproduce the void fraction, particle shape and average size of the real system. Simulation of the long-range diffusion of ethane in the bed over the Knudsen, transient, and molecular diffusion regimes is consistent with the PFG NMR measurements in yielding tortuosity factors which depend upon the regime of diffusion; more specifically, tortuosity factors defined in the conventional way are higher in the Knudsen than in the molecular diffusion regime. Detailed statistical analysis of the computed molecular trajectories reveals that this difference arises in a nonexponential distribution of the lengths and in a correlation between the directions of path segments traversed between collisions with the solid in the Knudsen regime. When the Knudsen tortuosity is corrected to account for these features, a single, regime-independent value is obtained within the error of the calculations. (c) 2007 American Institute of Physics.	en
heal.publisher	AMER INST PHYSICS	en
heal.journalName	Journal of Chemical Physics	en
dc.identifier.doi	10.1063/1.2567129	en
dc.identifier.isi	ISI:000244737400021	en
dc.identifier.volume	126	en
dc.identifier.issue	9	en