Diffusive hydrogen inter-cage migration in hydrogen and hydrogen-tetrahydrofuran clathrate hydrates

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Title: Diffusive hydrogen inter-cage migration in hydrogen and hydrogen-tetrahydrofuran clathrate hydrates
Authors: Cao, Huayu
English, Niall J.
MacElroy, J. M. Don
Permanent link: http://hdl.handle.net/10197/5234
Date: 7-Mar-2013
Abstract: Classical equilibrium molecular dynamics (MD) simulations have been performed to investigate the diffusive properties of inter-cage hydrogen migration in both pure hydrogen and mixed hydrogen-tetrahydrofuran sII hydrates at 0.05 kbar from 200 K and up to 250-260 K. For mixed H2- THF systems in which there is single H2 occupation of the small cage (labelled ‘1SC 1LC’), we found that no H2 migration occurs. However, for more densely-filled H2-THF and pure- H2 systems, in which there is more than single H2 occupation in the small cage, there is an onset of inter-cage H2 migration events from the small cages to neighbouring cavities at around 200 K. The mean square displacements of the hydrogen molecules were fitted to a mathematical model consisting of an anomalous term and a Fickian component, and non-linear regression fitting was conducted to estimate long-time (inter-cage) diffusivities. An approximate Arrhenius temperature relationship for the diffusion coefficient was examined and a rough estimation of the hydrogen hopping energy barrier was calculated for each system.
Funding Details: Science Foundation Ireland
Type of material: Journal Article
Publisher: American Institute of Physics
Copyright (published version): 2013 American Institute of Physics
Keywords: Molecular dynamics;Hydrogen hydrate;THF hydrate;Diffusion;Migration;Fickian
DOI: 10.1063/1.4793468
Language: en
Status of Item: Peer reviewed
Appears in Collections:Chemical and Bioprocess Engineering Research Collection

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