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Preparation of silicalite-1 composite membranes
Hrabánek, Pavel ; Bernauer, B. ; Zikánová, Arlette ; Krystl, V. ; Kočiřík, Milan
Silicalite-1 crystal layers were synthesised on stainless steel and ceramic supports. The stainless steel supports manufactured by Trumem Int. (USA) and ceramic supports manufactured by Carborundum Electrite (Czech Republic) were chosen to prepare silicalite-1 composite membranes. In the case of stainless steel silicalite-1 composite membrane, the applied synthesis process has been recently developed by Gora et.al [1]. It was observed that the presence of silicalite-1 seeds influenced the membrane quality. A number of crystallization steps also played an important role. Ceramic silicalite-1 composite membranes were prepared on ceramic supports with the layers of randomly oriented silicalite-1 crystals. The disadvantage of the ceramic supports was their large pore size distribution and roughness of the surface. For this reason, several coating steps using ceramic glaze had to be used to reduce the pore size distribution and non-uniformity of the surface.
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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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