Die Anwendung Thermoanalytischer Methoden zur Charakterisierung Faserbildender Organischer Hochpolymerer

Zusammenfassung An Hand von Literaturbeispielen und eigenen Arbeiten wird eine Übersicht über Anwendungsmöglichkeiten der Thermogravimetrie (TG) auf dem Gebiete der faserbildenden organischen Hochpolymeren gegeben. Die Untersuchung der relativen Thermostabilität, deren Veränderung durch Modifizierung der Polymeren oder den Zusatz von Stabilisatoren und die Ableitung kinetischer Daten werden besonders herausgestellt. Die Vorteile der Differentialthermogravimetrie sowie die Notwendigkeit isothermer thermogravimetrischer Untersuchungen zur Charakterisierung des thermischen Langzeitverhaltens werden erläutert. Abschließend werden allgemeine Einschränkungen und Empfehlungen für die Anwendung der TG, z. B. die Kombination mit anderen Charakterisierungsmethoden, genannt.

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A review on the application of thermogravimetry (TG) in the field of fiber-forming organic high polymers is given by examples from the literature and from the work of the author. The investigation of the relative thermostability, their changes by modification of the polymers or by addition of stabilizers and the calculation of kinetic values are particularly stressed. The advantage of derivative thermogravimetry and the necessity for isothermal thermogravimetric investigation to characterize the longtime behaviour of polymers are explained. Finally, general limitations of, and recommendations for, the application of TG, e.g. the combination with other methods of investigation, are mentioned.

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Résumé On donne une vue d'ensemble sur les possibilités d'application de la thermogravimétrie (TG) dans le domaine des hauts polymères organiques fibriformes, en se servant d'exemples pris dans la littérature et de travaux personnels. On dégage les données relatives à la stabilité thermique et aux changements qui s'y rapportent si l'on modifie le polymère ou si on le traite par des stabilisateurs; on présente également le calcul des paramètres cinétiques. On montre les avantages de la thermogravimétrie différentielle ainsi que la nécessité d'effectuer des essais thermogravimétriques isothermes pour caractériser le comportement thermique de longue durée. Enfin, on mentionne les limites et les avantages dans l'emploi de la TG, par exemple, l'emploi combiné avec d'autres méthodes de caractérisation.

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() . , , , . , . () .

     

Kinetics and thermodynamics of RuIII-EDTA complex catalyzed oxidation of diethylamine and triethylamine with molecular oxygen

The kinetics of oxidation of diethyl and triethylamine with molecular oxygen catalyzed by Ru^III (EDTA-H) (H₂O) complex has been studied at different temperatures (25–45 °C at pH 2.0 (=0.5 M KCl) as a function of amine concentration. The thermodynamic (G⁰, H⁰ and S⁰) and the activation parameters (H and S) for the reaction were computed.

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- , Ru^III (EDTA-H) (H₂O) (25–45°C) pH=2 (=0,5 M KCI) . (G⁰, H⁰ S⁰), (H S).

     

Numerical solution of direct kinetic problems

An algorithm is proposed to construct the righthand sides and the Jacobian matrix for a set of differential equations and a heat balance equation in terms of a given kinetic mechanism of a chemical reaction in a non-isothermal, constant-volume reactor. Its application is illustrated by the calculation of the dependence of the carbon monoxide explosion limit on the concentration of hydrogen added.

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. .

     

Reactivity of allyl (o-halophenyl) ethers with organonickel (0) complexes

The reactivity of allyl (o-halophenyl) ethers with zerovalent nickel complexes, with triphenylphosphine and pyridine as ligands, leading to benzo[b]furan derivatives has been checked. Cyclization products were not isolated, but deallylation, substitution, reduction and rearrangement products were obtained in low to moderate yields. Mechanisms are proposed to explain the formation of these side products.

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-(o-) , , [b] . , , , , . .

     

Influence of pore diffusion on the rate of n-heptane conversion on a Pt/Al2O3 catalyst under reforming conditions

Under reforming conditions, the rate of n-heptane conversion on a large Pt/Al₂O₃ catalyst grain, in contrast to that in the kinetic region, depends on the hydrogen to hydrocarbon mole ratio. The rate equation for the reaction on a large grain agrees well with the experimental results obtained by a gradientless method under pressure.

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- , , : . , .

     

Comparison of chemisorption and hydrogenolysis of ethane on transition metals

Data on chemisorption of ethane on transition metal blacks have been correlated with hydrogenolysis activity measurements. On Pt and Pd the rupture of the C–C bond seems to be a hindered process. Desorption of methane requires larger activation on Co and Ni than on Ru, Rh or or Ir blacks.

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. Pt Pd C–C . Co Ni, Ru, Rh Ir.

     

Influence of the basicity of butyl alcohols on their reactivity

Dehydration of various butyl alcohols in the presence of silicate catalysts with widely ranging strengths of their acidic centers has been studied. Increasing basicity of the reactants or of the strength of acidic centers of catalysts increases the reaction rate. On protonic reaction centers, dehydration proceeds through the equilibrium formation of hydrogen-bonded complexes.

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, . , . .

     

Methane and butane oxidation on aluminoplatinum catalysts

Methane and butane oxidation by oxygen (air) on once used AP-56 reforming catalyst has been studied at temperatures 663–773 and 493–533 K, respectively. Kinetic equations for these reactions are proposed and the difference in their oxidation mechanisms is discussed.

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-56 663–773 493–533 K, . . CH₄ C₄H₁₀.

     

Design and application of a liquid-flow adsorption micro calorimeter based on the Calvet-type DAK 1-1 microcalorimeter (USSR)

The construction and the properties of a liquid-flow adsorption microcalorimeter are described. The calorimeter is based on the commercially available Calvet-type DAK 1-1 microcalorimeter (USSR), which has been equipped with a flow system consisting of a pump, several sets of heat exchangers and an adsorption cell. The minimum detectable heat effect is 1W up to a flow rate of 30 cm³/h.Results on the application of the calorimeter to adsorption and desorption processes of nonionic (Triton X-100) and anionic (styrene phosphonic acid) surfactant solutions in water at an-Al₂O₃ surface are presented and discussed.

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Zusammenfassung Konstruktion und Eigenschaften eines Flüssigkeits-Strömungs-Adsorptions-Mikrokalorimeters werden beschrieben. Das Kalorimeter wurde weiterentwickelt aus dem Calvet-Mikrokalorimeter DAK 1-1 (USSR), das mit einem Strömungssystem aus einer Pumpe, verschiedenen Wärmeaustauschern und einer Adsorptionszelle ausgestattet wurde. Der kleinste nachweisbare Wärmeeffekt liegt bei 1W bis zu einer Durchflussgeschwindigkeit von 30 cm³ h^–1. Mit dem Kalorimeter erhaltene Messergebnisse zur Adsorption und Desorption wässeriger Lösungen von nichtionischen (Triton X-100) und anionischen (Styrenphosphonsäuren) Tensiden an-Al₂O₃ werden dargestellt und diskutiert.

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, 1-1 (), , , . 1 30 ³/. ( X–100) (- ) -l₂₃.

     

Thermogravimetric study of diatomites

The thermal curves of diatomites (kieselguhrs) in air display different profiles, depending on the type and quantity of impurities (carbonates, clays, etc.) present. TG and DTG runs can be used for a quick diagnosis of quality, but also give a nearly quantitative picture of the silica content of these minerals.

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Zusammenfassung In Abhängigkeit von Art und Menge der Verunreinigungen (Karbonate, Tonerde usw.) weisen die thermischen Kurven von Diatomiten (Kieselguhr) in Luft unterschiedlichen Verlauf auf. Einfache TG- und DTG-Untersuchungen können als Schnelldiagnose zur Bestimmung der Qualität benutzt werden und geben ausserdem noch ein nahezu quantitatives Bild über den Silikatgehalt dieser Mineralien.

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( ) , (, . .). , .

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The authors acknowledge the financial support of this work by the Comisión Asesora de Investigatión Cientifica y Técnica, Spain, through Project No. PR84-0151.     

Decomposition of dimethyl sulfide in the presence of Al2O3, and catalyst deactivation

The catalytic decomposition of dimethyl sulfide has been studied over the temperature range of 400–500 °C. The main reaction products are methylmercaptane, H₂S and methane. Catalyst deactivation is due to its coking during the reaction. The possibility of oxidative catalyst regeneration at 550 °C has been shown.

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400–500°C. , . , . 550°C.

     

AlPO4?ZrO2 catalysts, IV. Cyclohexene skeletal isomerization activity of systems obtained in ethylene oxide

The use of AlPO₄–ZrO₂ (weight ratio AlPO₄/ZrO₂=3) as catalyst systems obtained with ethylene oxide and subjected to different stages of heat treatments has been studied through their catalytic activity in the skeletal isomerization of cyclohexene to 1- and 3-methylcyclopentenes (1- and 3MCP). The apparent rate constants and selectivity to 1-MCP are used for an evaluation of the presence and amount of strong acid sites, the only ones capable of giving rise to skeletal isomerization. The decrease in catalytic activity as calcination increases is consistent with not only the decrease in the amount of acid sites measured vs. weaker organic bases but also with the decrease in Brönsted acidity, as shown by the decrease in O–H band intensity.

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AlPO₄–ZrO₂ ( AlPO₄/ZrO₂=3), , 1- 3- (1- 3-). 1- , . , , , O–H.

     

γ-Fe2O3 in Produkten der Thermischen Zersetzung von Eisen(III)-Akrylat und Eisen(III)-polyakrylat

Zusammenfassung In diesem Beitrag wurden die Darstellungsmethode von Eisen(III)-akrylat und Eisen(III)-polyakrylat sowie die grundsätzlichen physikalisch-chemischen Eigenschaften derselben beschrieben. Die genannten Verbindungen wurden bei freiem Luftzutritt im Temperaturbereich von 120–600° erwärmt. Zwecks Identifizierung der in den Pyrolyseprodukten auftretenden ferromagnetischen Phasen, wurden Untersuchungen der magnetischen Suszeptibilität, der spezifischen Magnetisierung und der chemischen Zusammensetzung durchgeführt. Auch wurde die röntgenographische Analyse angewandt. In Präparaten die bei Temperaturen von 320–460° dargestellt wurden, konnte die Anwesenheit von- Fe₂O₃ festgestellt werden. Ein maximaler Gehalt dieser Phase trat im Temperaturbereich von 420–440° auf.

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Methods of preparation and some physico-chemical properties of iron(III) acrylate and iron(III) polyacrylate are described. These two compounds undergo transformations when heated in air from 120 up to 600°, resulting in a ferromagnetic modification of iron oxide (-Fe₂O₃) in the range 320–460°, and in-Fe₂O₃ at higher temperatures. In the case of Fe(III) acrylate the maximum specific magnetization reveals the product to be obtained at 440°; with Fe(III) polyacrylate this property is observed at 420°.

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Résumé On décrit les méthodes de préparation ainsi que quelques propriétés physicochimiques de l'acrylate de fer(III) et du polyacrylate de fer(III). Chauffés dans l'air, ces deux composés subissent entre 120 et 600° des transformations dues à la transformation ferromagnétique de l'oxyde de fer (-Fe₂O₃) entre 320 et 460° et à celle de-Fe₂O₃ à plus haute température. Dans le cas de l'acrylate de fer(III) le produit obtenu est mis en évidence par un maximum d'alimentation spécifique à 440°. Celui-ci s'observe à 420° dans le cas du polyacrylate de fer(III).

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- — (III). 120–600° (-Fe₂O₃) 320–460°. -Fe₂O₃. (III) 440°, (III) - 420°.

     

Liquid-phase oxidation of propylene to propylene glycol acetates over Pd/C and Pt?Pd/C: Effect of platinum on catalyst activity and metal dispersity

Kinetics of oxidation of propylene to propylene glycol and its acetates in acetic acid solutions of lithium nitrate over Pd/C and Pd–Pt/C catalysts has been studied. Catalysts were investigated using X-ray phase analysis and electron microscopy. Platinum introduction into catalyst increases the metal dispersity and the catalyst stability but produces no effect on the nature of surface sites active in propylene oxidation.

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Pd/C Pd–Pt/C. . , , , .

     

Radical addition of methyldichlorosilane to 1-hexene and acetylene

Radical interaction of methyldichlorosilane with 1-hexene (B) and acetylene (C) is shown to form addition products. The calculated Arrhenius parameters for the relative rate constant of the addition reaction amount to lg A_B/A_C=0.0±0.2 and E_B–E_C=–7.8±0.5 kJ M^–1.

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, 1- (B) (C) . , : A_B/A_C=0,0±0,2; E_B/E_C=–7,8±0,5 /.

     

Investigation of the pore structure of Raney nickel catalysts

Ar and N₂ adsorption and capillary condensation studies at 77.4 and 84K on Raney nickel catalysts modified by Ti, V, Cr, Mn, Zr, Mo, Ta, W, Re and on BAU char coal show that at 77.4K, in pores with d_eff>100Å, argon exists in the solid state.

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Ar N₂ 77,4 84°K - , Ti, V, Cr, Mn, Zr, Mo, Ta, W, Re , d>100 Å 77,4 °K .

     

IR study of adsorbed piperidine dehydrogenation on oxidic or sulfided Ni?W/Al2O3 catalysts

IR spectroscopy has been used to follow the transformation at different temperatures of piperidine chemisorbed on oxidic or sulfided Ni–W/Al₂O₃ catalysts. Formation of an intermediate species, possibly tetrahydropyridine, and pyridine is evidenced. Their formation temperature on the sulfided samples accounts for the catalyst activity in pyridine hydrogenation under H₂ pressure.

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- , Ni–W/Al₂O₃, . , , . .

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This work was supported by the Groupement scientifique Hydrotraitement catalytique (CNRS-IFP, TOTAL. ELF).     

Poisoning effect of carbon monoxide on the desorption process of hydrogen from palladium

The desorption of H₂ from clean and CO-poisoned Pd wires was studied by a temperature programmed desorption technique. Poisoning effect of CO on H₂ desorption process can be accounted for in terms of blockage of the surface sites for the recombination of H atoms.

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H₂ , CO, - . CO H₂ , , , .

     

Kinetics of the thermal decomposition of alkaline earth metal hydrofluorides

The thermal stability of alkaline earth metal hydrofluorides was studied by means of a Derivatograph. The values of the activation energy, reaction order and rate constant were determined. The comparison of the kinetic parameters of the decomposition process for the complete series of hydrofluorides studied led to a certain regularity in the differences in their thermal stabilities and its correlation with the strength of the hydrogen bond in their structure.

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Zusammenfassung Die thermische Stabilität von Erdalkalihydrofluoriden wurde mit Hilfe eines Derivatographen untersucht, die Werte der Aktivierungsenergien, der Reaktionsordnung und der Geschwindigkeitskonstanten bestimmt. Der Vergleich der kinetischen Parameter des Zersetzungsvorganges wies auf eine gewisse Regelmäßigkeit in ihrer verschiedenen thermischen Stabilität, die in Zusammenhang mit der Stärke ihrer strukturalen Wasserstoffbindung steht.

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Résumé On a étudié la stabilité thermique des hydrogénofluorures des métáux alcalinoterreux et déterminé les valeurs des énergies d'activation, des ordres de réaction et des constantes de vitesse de réaction à l'aide d'un Dérivatographe. Après comparaison des paramètres cinétiques on a pu établir une certaine régularité dans le changement de la stabilité thermique en corrélation avec la force de liaison de l'hydrogène dans la structure.

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