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Vliv parciální neutralizace na katalytickou aktivitu ionexů
Holub, Ladislav ; Hanková, Libuše ; Jeřábek, Karel
Concentration of acid centers in a commercional ion exchanger catalyst was controlled by partial neutralization of sulfonic groups with various primary, secondary and tertiary amines of different molecular size. The efect of acid centres concentration on the activity of ion exchanger catalyst was tested by measurements of initial reaction rate of reesterification of ethyacetate with methanol in a CSTR-type reactor. There was found that the slope of the dependence of the catalyrtic activity on the degree of the resin neutralization strongly depends on the amine basicity.
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Hydrogenace thymolu ve zkrápěném reaktoru
Dudas, J. ; Hanika, Jiří ; Lepuru, J. ; Barhuysen, M.
the main objective of the investigation was to collect experimental data for scale up for the hydrogenation of thymol in a trickle bed reactor. Based on bench scale data and process simulation using physico-chemical parameters and measured reaction kinetics, a pilot scale reactor has been designed during this study. One major focus of the work was the determination of the limetife of a commercially available nickel catalyst.
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Kvalitativní analýza a řízení v závislosti na vstupních úodmínkách modelu protiproudé plněné kolony
Akramov, T. A. ; Jiřičný, Vladimír ; Staněk, Vladimír
In recent papers a mathematical model of the transients of the hydrodynamic of counter-current column was formulated. It was used for describing the overshoot phenomenon on the transient profiles of liquid holdup. These overshoots were observed experimentally when the bed was exposed to a sudden increase of either gas or liquid inlet velocity. Another condition for the appearance of the overshoots was that the step change in inlet velocity brings the system in proximity of the flooding point. The formulated model could under some conditions give a good description of the time behavior of the mean liquid holdup. In particular this model is capable of predicting and describing the conditions of the overshoot phenomenon after an imposed change of inlet velocity of liquid or gas. The problem now is to find out the response of the system periodical step changes in inlets velocity of gas or liquid. .
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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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