Ideal and mixture permeation selectivity of flexible prototypical zeolitic imidazolate framework - 8 membranes

Sitprasert, C., Wang, F. Y., Rudolph, V. and Zhu, Z. H. (2014) Ideal and mixture permeation selectivity of flexible prototypical zeolitic imidazolate framework - 8 membranes. Chemical Engineering Science, 108 23-32. doi:10.1016/j.ces.2013.12.041


Author Sitprasert, C.
Wang, F. Y.
Rudolph, V.
Zhu, Z. H.
Title Ideal and mixture permeation selectivity of flexible prototypical zeolitic imidazolate framework - 8 membranes
Journal name Chemical Engineering Science   Check publisher's open access policy
ISSN 0009-2509
1873-4405
Publication date 2014-04-28
Year available 2013
Sub-type Article (original research)
DOI 10.1016/j.ces.2013.12.041
Volume 108
Start page 23
End page 32
Total pages 10
Place of publication Kidlington, Oxford, United Kingdom
Publisher Pergamon
Collection year 2014
Language eng
Formatted abstract
Permeance, ideal and mixture permeation selectivity have been evaluated based on molecular simulations of gas adsorptions by the grand canonical Monte Carlo simulation and diffusion by molecular dynamics simulation under a flexible framework. Additional transport phenomena are also obtained using transition state theory under rigid framework assumptions. A number of gas systems in the simulation involving H2, CO2, CH4, N2, O2 and Ar penetrating through a thin layer of ZIF-8 membrane are analyzed and compared with permeance, ideal and mixture permeation selectivity experiments. Three contributions have been achieved in this work. Firstly, it is demonstrated that the assumption of a rigid framework may be sufficient for simulating adsorption isotherms while diffusivity requires a flexible framework, especially when a diffusing molecule is bigger than the pore window of the MOFs, with an appropriate force-field and charges. Secondly, simulations of the ideal permeation selectivity are higher than those of mixture permeation selectivity. However, both calculations with flexible framework accuracy may be acceptable for the purpose of screening membrane materials when compared with experiments, especially the permeation selectivity of an equimolar mixture. Finally, even though simulated isotherms, diffusivity and mixture selectivity are consistent with available experiments and the same data have been used for estimating permeance of the membrane, the difference between the estimation and measurement of the permeation at low pressure is considerable. Therefore, it is confirmed that the effects of defections and multi-scale (macroscopic) diffusion cannot be ignored.
Keyword Adsorption isotherms
Diffusion
Flexible ZIF-8
Molecular simulations
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Published online 31 December 2013

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemical Engineering Publications
Official 2014 Collection
 
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