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Mesoscopic modeling of binary diffusion through microporous zeolite membranes

Published online by Cambridge University Press:  11 February 2011

Mark A. Snyder  and
Dionisios G. Vlachos
Mark A. Snyder
Affiliation:
Department of Chemical Engineering and Center for Catalytic Science and Technology (CCST), University of Delaware, Newark, DE 19716–3110, U.S.A.
Dionisios G. Vlachos
Affiliation:
Department of Chemical Engineering and Center for Catalytic Science and Technology (CCST), University of Delaware, Newark, DE 19716–3110, U.S.A.
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Abstract

The mesoscopic framework describing single-component diffusion through microporous materials is extended here to characterize binary diffusion in the absence of intermolecular forces. Two diffusion mechanisms, single-file diffusion characteristic of confined pore structures and species-species exchange consistent with diffusion modes in less-confined pore topologies, are incorporated at the Master Equation level. Derived fundamentally via rigorous coarse-graining of the underlying Master Equation, the binary mesoscopic relation is validated via direct comparison to gradient continuous time Monte Carlo (G-CTMC) simulations. We further show the capability of this fundamentally derived model to capture the macroscopic diffusion phenomenon of ‘overshoot’ or ‘roll-up’ in the transient uptake and flux. Exploration of the species-species exchange mechanism reveals its strong effect on the transient ‘overshoot’ behavior through relaxation of the constrained single-file diffusion.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 752: Symposium AA – Membranes–Preparation, Properties and Applications , 2002 , AA7.8
Copyright
Copyright © Materials Research Society 2003

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References

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