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Process-Based Model of Mixed-Matrix Membrane
Čapek, P. ; Hejtmánek, Vladimír ; Veselý, M. ; Sysel, P. ; Kočiřík, Milan ; Brabec, Libor ; Zikánová, Arlette ; Bernauer, B. ; Fíla, V.
The focus of this contribution was on the formulation and verification of a process-based model of the mixed-matrix membrane that consisted of the polyimide matrix synthesized from the monomers 4,4’-(hexafluoroisopropylidene)diphtalic anhydride and 4,4’-oxydianiline, and silicalite-1. When a solution of a polyimide precursor in N,N-dimethylformamide was ready, silicalite-1 particles were dispersed in the solution and the dispersion was subsequently cast on a Teflon support plate. An initial mass ratio of silicalite-1 and polyimide was about 1:1. After solvent removal, the films were heated in subsequent steps up to 230°C for two hour. From a process-based model point of view, a key operation of the entire synthesis was slow sedimentation of silicalite particles in the viscous solution. Preliminary observation of 2D cuts through the solid membrane in a scanning electron microscope revealed that there were a lot of contacts among the silicalite particles. Therefore, a sequential (ballistic) deposition algorithm, well representing sedimentation in a low-energy environment, was used to create an off-lattice model of spatial distribution of the silicalite particles in the polyimide matrix.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22012102413461 - PDF
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Reconstructed 3D Microstructure and Effective Diffusivity of a Zeolite-Polyimide Mixed Matrix Membrane
Čapek, P. ; Hejtmánek, Vladimír ; Fryčová, M. ; Sysel, P. ; Kočiřík, Milan ; Brabec, Libor ; Zikánová, Arlette ; Bernauer, B. ; Fíla, V.
In our work we focused on a two-phase system consisting of the polyimide matrix synthesized from the monomers 4,4’-(hexafluoroisopropylidene)diphtalic anhydride (6FDA) and 4,4’-oxydianiline (ODA), and silicalite-1 [3, 4]. Its microstructure on the scale capturing the morphology of silicalite particles was reproduced by means of stochastic reconstruction. Then, effective diffusivity of an arbitrary fluid in the reconstructed composite material was determined by exploiting random walk simulation. Resulting values were compared with the corresponding values obtained using two traditional correlations for conductivity of composite materials. Image processing and analysis as the first step of stochastic reconstruction was a bit inexact in terms of an estimation of the volume fractions of both phases.
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Separace uhlovodíků a CO2 na zeolitických MFI membránách
Dung Cong, T. ; Fíla, V. ; Hrabánek, Pavel ; Cílová, Z. ; Zikánová, Arlette
MFI zeolite membranes were prepared on stainless steel and ceramic supports by using hydrothermal synthesis method. The synthesized zeolite layers were compact and composed of randomly oriented crystals. Single component gases such as He, N2, CO2, SF6, CH4, i-C4H10, n-C4H10 and SF6 were used to test membrane permeation and separation characteristics. The effects of temperature and pressure drop on the separation properties of the membranes were also investigated using Wicke-Kallenbach method. Separation factors measured for CO2/CH4 and butane isomer mixtures were in the range of 1.2 – 4.1 and 5 – 20, respectively, depending on the operating conditions of the experiments and particular membranes.
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Preparation and Characteristics of Porous Supports for Microporous Membranes Based on Al2O3 and SiO2
Fíla, V. ; Hrabánek, Pavel ; Juristová, K. ; Zikánová, Arlette ; Andertová, J. ; Bernauer, B.
Inorganic membranes have been used for separation of various liquid and gas mixtures due to their high mechanical and chemical resistance at elevated temperatures and pressures. The materials such as stainless steel, ceramics, polymers are available for preparation of the inorganic membranes. This paper is focused on the preparation and characterization of the composite membranes consisting of a ceramic support and layer of zeolite. The first part of the paper deals with the preparation of the porous ceramic supports, which are made using dry molding of a ceramic suspension mixed with the organic dispersant. The supports were characterized by permeation of N2, mercury porosimetry and SEM. The second part of the paper is focused on the preparation of microporous zeolite (MFI) layers on the supports. These microporous membranes were characterized by permeation and separation of H2 and iso-butane.
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Vývoj anorganických nosičů vhodných pro depozici mikroporésních vrstev – syntéza a charakterizace
Juristová, K. ; Fíla, V. ; Andertová, J. ; Zikánová, Arlette ; Bernauer, B. ; Lhotka, M.
The present study is focused on the preparation of porous supports (ceramic, glass) and thin microporous layers (zeolite, polyaluminum chlorid (PAC), silicalite-1), which are suitable for application in the catalysis, membrane technology and biotechnology. The modification of ceramic Al2O3 support and its preparation by the slip-casting method is discussed here. The optimal conditions for modification of ceramic support using the PAC and the optimal conditions for slip-casting support design were proposed and experimentally verified. The second part of the work deals with the synthesis of boro-silicalite glass. The characterization of the supports by SEM, mercury porosimetry and by permeation measurements are discussed.
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