Methods for finding steady-state solutions of mathematical models for chemico-technological schemes

Gradient and Newton methods are suggested for searching for steady-state solutions of chemico-technological schemes to obtain synthetic fuels.

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- .

     

Gas phase thermolysis of phenylazoethane

The pyrolysis of phenylazoethane has been studied in a stirred-flow system using cyclohexene as carrier gas at sub-ambient pressures, in the temperature range of 380–416°C. The activation energy is examined in relation to the C–N bond dissociation energy and the heat of formation of the phenyldiazenyl radical.

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, - 380–416°C. C–N .

     

Conversion of dehydrolinalyl acetate in catalytic hydrogenation on metals

Low selectivity of dehydrolinalyl acetate (DeHLA) hydrogenation into linalyl acetate and ester group detachment are predicted in accordance with quantum-chemical data obtained for its homologue dimethyl ethynyl carbinol acetate. Experimental data are confirmed by theoretical calculations. DeHLA hydrogenation produces a variety of products.

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, - . . .

     

Photolysis of alkylperoxy radicals frozen out from the gas phase

Photolysis of alkylperoxy radicals with 250 nm light has been studied and proposed for investigation of heterogeneous-homogeneous reactions by freezing out radicals from the gas phase and their ESR identification. Using amine decomposition reaction in the presence of O₂ as an example, we have shown that photodissociation of frozen peroxy radicals can be used to reduce the structure of initial alkyl radicals.

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- 250 . , .

     

Influence of pressure reduction on the shapes of thermoanalytical curves of red muds

The effect of reduction of pressure on the shapes of the TG, DTG and DTA curves and the mass-spectra of hydroxide and carbonate phases was investigated in some typical Hungarian red muds. The pressure change caused different decomposition rates of the phases and resulted in better separation of the overlapping thermal curves; this led to advantages as regards phase analysis. For phase analysis the red muds were extracted with water, and the extracts and solid residues were identified by IR- and X-ray methods.

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Zusammenfassung Die Wirkung der Druckänderung auf die Form der TG-, DTG- und DTA-Kurven, sowie der MS-Spektra der Hydroxid- und Carbonatphasen in einigen typischen ungarischen Rotschlamm-Sorten wurde geprüft. Die Druckänderung verursachte verschiedene Zersetzungsgeschwindigkeiten der Phasen, führte zur besseren Auftrennung der sich überlappenden thermischen Kurven, und war ausserdem auch hinsichtlich der Phasenanalyse vom Vorteil. Zur Phasenanalyse wurden die Rotschlämme mit Wasser extrahiert und die Extrakte und festen Rückstände mittels IR- und Röntgenmethoden identifiziert.

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Résumé On a étudié dans quelques espèces typiques de boues rouges de Hongrie l'effet des variations de pression sur la forme des courbes TG, TGD et ATD ainsi que les spectres de masse des phases hydroxyde et carbonate. La variation de la pression entraîne des vitesses de décomposition différentes. Il en résulte une meilleure séparation des phénomènes dans le cas où ceux-ci se chevauchent ainsi que des avantages du point de vue de l'analyse des phases. L'analyse des phases présentes dans les boues rouges a été effectuée par extraction à l'eau. Les extraits et les résidus solides ont été identifiés par spectrométrie infrarouge et par diffraction des rayons X.

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, - . , , . .

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Paper presented at the Scientific Session on Thermal Analysis held at Balatonfüred, Hungary, on 14–16 October 1976.     

Catalytic oxidation of octene-1 in the presence of palladium(II) salts and heteropolyacids

In the presence of the catalytic system (PdSO₄+HPA), where HPA=H₉PMo₆V₆O₄₀, octene-1 is found to be selectively (95%) oxidized to octanone-2. The optimum concentration ratio for catalyst stability is [HPA]:[PdSO₄]=30–40. The substitution of PdCl₂ for PdSO₄ leads to the formation of all three isomeric octanones without decrease of the overall selectivity. Effective rate constants and the apparent activation energy have been determined in the temperature range from 60 to 80 °C.

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(PdSO₄+), =H₉PMo₆V₆O₄₀, -1 ( 95%) -2. []:[PdSO₄]=30–40. PdSO₄ PdCl₂ . 60–80 °C.

     

Asymmetric hydrogenation in the presence of polycyclic chiral phosphines, II /8/

The enantiomers of trans-11, 12-bis-(diphenylphosphinomethyl)-9, 10-dihydro-9,10-ethanoanthracene and its perhydrogenated derivative were prepared and used as ligands in the asymmetric hydrogenation of prochiral olefinic substrates. Different selectivities and partiallyhigh optic al yields could be observed

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-11, 12--()-9, 10--9,10- . .

     

Ammoxidation of cyclohexanol to adiponitrile on vanadium oxide

The reaction pathway of ammoxidation of cyclohexanol to adiponitrile (ADN) on vanadium pentoxide catalyst has been investigated. ADN was produced directly via adipic acid obtained from oxidation of cyclohexanone. The main end-products were carbon dioxide and benzene.

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() V₂O₅. , . .

     

Study of selective dissociation in C6F5H?C6F5D mixtures induced by intense CO2 laser pulses

Irradiation of a C₆F₅H–C₆F₅D mixture at 1 Torr by a tunable CO₂ pulse laser brings about chiefly dissociation of one component depending on the frequency of emission absorbed by the proper molecules. The addition of radical acceptors increases the selectivity by suppressing secondary reactions.

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C₆F₅H C₆F₅D 1 CO₂-, , . .

     

Kinetics of edta catalyzed oxidation of I? by Cr(VI)

The activity of various iron-containing ore catalysts during hydrogenation of Kansk-Achinsk lignite into liquid products in H-donor solvent (tetraline) has been studied. Ore samples contained pyrite, hematite and magnetite minerals. The most active appear to be pyrite samples. The catalytic effect of ore systems is, apparently, associated with the fact that during hydrogenation more active than tetraline H-donors are formed due to the hydrogenation of polycyclic aromatic molecules produced by thermal destruction of lignite.

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- H- . , , . , . , , , , , .

     

Liquid-phase hydrogenation of cyclohexene by dihydrogen in the presence of dimolybdenum tetraacetate

Catalytic liquid-phase hydrogenation of cyclohexene in DMF by dihydrogen in the presence of dinuclear bridged complex Mo₂(OAc)₄ has been studied. A kinetic equation for the steady-state rate of cyclohexene hydrogenation and the activation parameters are suggested.

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Mo₂(OAc)₄. .

     

Mechanism of carbon monoxide oxidation on nickel oxide and its solid solutions

On the basis of studying the isotope exchange of oxygen and the position of the Fermi level in the system MiO–Li_xNi_1–xO, an explanation is proposed for the compensation effect in the reaction of CO oxidation on nickel oxide and its solid solutions.

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NiO–Li_xNi_1–xO CO .

     

A thermal study on moisture absorption by epoxy composites

The water sorption kinetics of an epoxy matrix-carbon fiber composite with different degrees of polymerization was studied. It was observed that the diffusion coefficients, determined perpendicularly to the fiber direction, are increased by increasing the cure degree. Only a small portion of the bonded water is released when the specimen are heated to 200 °C.The effects of moisture on some properties of the composite were also investigated. TheT _g values determined on fully polymerized samples, show lowerings of 70 degrees; moreover, the plasticization power of the bonded water increases on decrease of the temperature of conditioning of the specimens.Finally, the water present in the matrix considerably reduces the thermal stability of the composite.

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Zusammenfassung Es wurde die Wassersorptionskinetik eines Graphitfaserverbundstoffes auf Epoxymatrixbasis mit verschiedenen Polymerisationsgraden untersucht. Es zeigte sich, daß die senkrecht zur Faserrichtung bestimmten Diffusionskonstanten mit anwachsendem Vernetzungsgrad zunehmen. Beim Erhitzen des Materials auf 200 °C wird nur ein geringer Teil des gebundenen Wassers abgegeben. Der Einfluß des Feuchtgehaltes auf einige Eigenschaften des Verbundstoffes wurde ebenfalls untersucht. Die an vollkommen polymerisierten Proben bestimmtenT _g Werte zeigen eine Abnahme von 70 Grad; die Plastifizierungswirkung des gebundenen Wassers ist um so höher, je niedriger die Konditionierungstemperatur der Probe war. Das in der Matrix gegenwärtige Wasser senkt beträchtlich die Wärmebeständigkeit des Verbundstoffes.

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- . , , , . 200 °. . Tg, , 70 °. . , , .

     

Kinetics and mechanism of the oxidation of benzyl alcohol by potassium chlorochromate

The kinetics of the oxidation of benzyl alcohol by potassium chlorochromate, KCrClO₃, has been studied in dimethyl sulfoxide-dichloromethane medium. The reaction is catalyzed by acid. The effects of temperature and solvent composition were studied and activation parameters evaluated. Probable mechanisms are discussed.

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, KCrClO₃, . . . .

     

Study of CO and H2 sorption on supported bimetallic Pd?Pb catalysts

With increasing the lead content both CO and hydrogen sorption drop considerably. The influence of lead can be observed starting from a concentration of 0.5%. This may indicate that the surface is enriched in lead atoms.

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CO, H₂. , 0,5%. .

     

Review of some metallurgical problems suitable for quantitative calorimetric treatment

A review is given of various metallurgical problems treated in the author's laboratory, for which quantitative calorimetry gave very valuable information. Measurements of thermodynamic data for phase diagram calculations, vacancies in ordered alloys, annealing of steels, and the recovery and crystallization of amorphous alloys are successively examined.

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Zusammenfassung Es wird eine Übersicht über verschiedene, in unserem Laboratorium bearbeitete metallurgische Probleme gegeben, für die durch quantitative Kalorimetrie sehr genaue Informationen erhalten werden. Es wird auf Messungen thermodynamischer Daten für Phasendiagrammberechnungen, auf Fehlstellen in geordneten Legierungen, auf das Tempern von Stahl sowie auf Aufarbeitung und Kristallisation von amorphen Legierungen eingegangen.

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, . , , .

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Dedicated to Professor Dr Kurt Komarek on his 60th birthday.     

Solid-liquid equilibrium of the phenanthrene-fluorene system

The solid-liquid equilibrium of the phenanthrene-fluorene system was investigated by differential thermal analysis. Supplementary measurements were applied too: crystal decay temperature examination and melting point examination with a Boetius microscope. The investigated system forms a stable solution with a minimum at 58 mole% of phenanthrene and a temperature of 95.5°.

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Zusammenfassung Das fest-flüssig-Gleichgewicht des Systems Phenantren-Fluoren wurde durch die Differentialthermoanalyse untersucht. Als ergänzende Messungen wurden eingesetzt: die Untersuchung der Kristallzerfallstemperatur und die Prüfung des Schmelzpunktes mit dem Mikroskop nach Boetius. Das untersuchte System bildet eine stabile Lösung mit einem Minimum bei 59 Mol% Phenantren und einer Temperatur von 95.5°C.

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Résumé L'équilibre solide-liquide du système phénanthrène-fluorène a été étudié par analysethermique différentielle. Des essais complémentaires ont également été effectués: détermination de la température de disparition des cristaux et détermination du point de fusion au microscope suivant Boetius. Le système étudié forme une solution stable avec un minimum à 58 mol% de phénanthrène et une température de 95.5°.

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- -. . 5S .% 95.5°.

     

Differential thermal analysis studies of chemical systems in sealed cells

Many chemical systems illustrating major reaction types may be conveniently studied by differential thermal analysis. The problems of vaporization and sublimation have been avoided through the use of sealed glass vials. Sample sizes are in the range of 10 to 100 milligrams. This size though small is still more than adequate for chemical analysis by instrumental methods such as infrared spectroscopy and gas chromatography.

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Zusammenfassung Die Differentialthermoanalyse ist zur Untersuchung vieler Systeme mit den wesentlichsten Reaktionstypen geeignet. Durch Verdampfen und Sublimieren verursachte Veränderungen beseitigt man durch die Verwendung verschlossener Glasampullen. Die Größe der Probe bewegt sich von 10 bis 100 mg. Diese Menge reicht aus, um eine chemische Analyse durch Infrarotspektroskopie oder Gaschromatographie durchzuführen.

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Résumé De nombreux systèmes chimiques illustrant les principaux types de réaction peuvent être étudiés d'une manière commode par analyse thermique différentielle. On élimine les problèmes provenant de la vaporisation et de la sublimation par l'emploi d'ampoules de verre scellées. On prend des échantillons de 10 à 100 mg. Cette quantité, quoique déjà faible, est plus que suffisante pour faire l'analyse chimique par des méthodes instrumentales comme la spectroscopie infrarouge et la chromatographie en phase gazeuse.

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, , . . 10–100 . , , , .

     

Determination of liquid vapour adsorption and desorption on and from solids by means of the derivatograph II

Studies of water adsorption and desorption on silica gel with a modified derivatograph are described. The dynamic gas chromatography step profile method was used to determine isotherms of adsorption and desorption from the TG curve. The obtained isotherms agree with those from other methods. The properties of surface liquid layers can be investigated by this method.

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Zusammenfassung Die Untersuchung der Adsorption und Desorption von Wasser an Silikagel mittels eines modifizierten Derivatographen wird beschrieben. Die dynamische gaschromatographische Stufenprofilmethode wurde zur Bestimmung der Ad- und Desorptionsisothermen aus den TG-Kurven herangezogen. Die erhaltenen Isothermen stimmen gut mit denen nach anderen Methoden bestimmten überein. Die Eigenschaften flüssiger Oberflächenschichten können mit dieser Methode untersucht werden.

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