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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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Kompozity na bázi silikalit-1- polyimidy
Šnáblová-Fryčová, M. ; Sysel, P. ; Chánová, E. ; Bernauer, B. ; Kočiřík, Milan
Two methods of adhesion improvement between the polyimide matrix and zeolite (silicalite-1) were examined. Firstly, there were prepared polyimide precursors (polyamic acids) with controlled molecular weight terminated with 3-aminopropyltriethoxysilane. The transformation of polyamic acids into polyimides upon heating was accompanied by the formation of Si-O-Si bonds between the polymeric matrix and hydroxyl groups on zeolite surface. Secondly, the polyimide was modified using rubbery poly(dimethylsiloxane)s. Relations between film properties (i.e. interfacial adhesion and accessibility of zeolite channels for species) and film composition were studied both for unfilled and filled PI films.
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Propustnost podél hranic zrn v dobře definovaných polykrystalických vrstvách silikalitu-1 a v samostatných krystalech
Brabec, Libor ; Zikánová, Arlette ; Kočiřík, Milan
Self-supporting silicalite-1 layers were grown on mercury surface from clear solutions at temperatures 140-180 oC. Large silicalite-1 crystals were synthesized using TPABr as template. Layer morphology and thickness were characterized by SEM. Phase purity of silicalite-1 and orientation of crystals were determined by XRD. Layers with the thickness > 40 .mu.m were found to be highly compact. Wet HF etching of as-synthesized polycrystalline silicalite-1 layers caused formation of deep sharp slits at grain boundaries and thus it visualized them. Contrary to this result etching of calcined layers led to a kind of a negative image represented by preserved thin shells at crystal boundaries which were found to be impregnated by carbon residues formed during template removal. Results of etching experiments give a strong indication of the existence of a thin amorphous silica interface between neighbouring crystals. The etching patterns were somewhat different for large silicalite-1 crystals.
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