A transient permeation-based method for composite zeolite membranes characterization

International audienceAn in situ nondestructive characterization method for zeolite composite membranes, based on transient permeation experiments, is proposed in the present article. This technique allows an accurate evaluation of the zeolite selective layer thickness as well as the thermodynamic and transport properties of sorbing hydrocarbons. To this end, a dynamic model representing mass transport phenomena within the whole permeating module is derived. In order to get the crystal layer properties, a two‐step experimental approach is required. The zeolite layer effective thickness is first estimated with the permeation of a nonadsorbing species like hydrogen. Then, the adsorption equilibrium constants and the diffusion coefficients of butane isomers are determined. Three membranes obtained by different synthesis procedures are studied in the Henry domain. The estimated values of the equilibrium constants and diffusion coefficients for normal butane and isobutane are favorably compared with existing literature data. © 2008 American Institute of Chemical Engineers AIChE J, 200

A Transient Method for Mass-Transfer Characterization Through Supported Zeolite Membranes: Extension to Two Components

RAFFINAGE+MTFIn a previous work (Courthial et al.) a transient state characterization method for zeolite supported membranes has been proposed and tested for single components in the Henry domain. An extension of the method to single components beyond the Henry domain and to binary mixtures is described. Since the method is based on experiments performed within the linear domain, the dynamic model previously developed for single components in the Henry domain is extended. The parameter estimation procedure that is described is based on a deep analysis of the model structure with respect to its structural identifiability properties. Some experimental results concerning pure n-butane as well as isobutane/ n-butane mixtures transport through mordenite framework inverted (MFI)-supported membranes are finally shown to illustrate the technique. (C) 2012 American Institute of Chemical Engineers AIChE J, 59: 959-970, 201