Ausbrennen von Kohlenstoffhaltigen,in den Ziegelrohstoff Eingepressten Stoffen

Zusammenfassung Die Kinetik der Ausbrennung organischer Stoffe im Ziegelscherben wird verfolgt und erläutert. Die Möglichkeiten der Beeinflussung des energetischen Aufwandes unter Nutzung moderner analytischer Methoden sind festzustellen. Bei einem diffusen Ausbrennen ist die Dichte und Durchlässigkeit des Scherbens massgebend. Praktische Anwendungsmöglichkeiten verschiedener auszubrennender Stoffe in unterschiedlichen Rohstoffen der Ziegelindustrie.

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The kinetics of burn-out of organic materials in bricks has been followed and explained. It is to establish that using new analytical methods the energy consumption can be influenced. The diffuse burn-out is determined by the density and permeability of bricks. There is a possibility for practical use of the results in the brick-industry with the different compounds to be burnt out from various raw materials.

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Kinetics of thermal decomposition of pyrite in an inert atmosphere

The thermal decomposition of pyrite in an inert atmosphere was studied in order to obtain a detailed knowledge of the kinetics and mechanism of the reaction 2 FeS₂=2FeS+S₂, which is one of the methods of producing elementary sulphur. The process was studied under isothermal conditions at temperatures of 600, 660, 700, 750, 800 and 850 °C in a nitrogen atmosphere, by means of a thermobalance. The rate-controlling processes were determined and their kinetic parameters were calculated. The optimum temperature for the process was found to be 800 °C.

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Zusammenfassung Es wurde die thermische Zersetzung von Pyrit in inerter Atmosphäre bestimmt, um detaillierte Informationen über Kinetik und Mechanismus der Reaktion 2 FeS₂=2FeS+S₂, einer der Darstellungsreaktionen von elementarem Schwefel zu erlangen. Der Vorgang wurde mittels einer Thermowaage unter isothermen Bedingungen bei Temperaturen von 600, 660, 700, 750, 800 und 850 °C untersucht. Es wurden die geschwindigkeitsbestimmenden Schritte bestimmt und deren kinetische Parameter errechnet. Als Optimumtemperatur für diesen Prozeß erwies sich 800 °C.

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- 2FeS₂=2FeS + S₂, . 600, 660, 700, 750, 800 850 ° . , 800°.

     

Effect of acid-base properties of oxide catalysts in the oxidative dehydrodimerization of olefins

The dependence of the activity of tin-containing oxide catalysts on their basicity and acidity has been examined. The rate of oxidative dehydrodimerization of olefins is shown to be determined by the mobility of allyl compounds depending on the catalyst acid properties.

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. , , .

     

Identification of exchange-coupled V4+ and Cu2+ ions in Cu?V?Mo oxide systems

ESR studies of X(CuO)·V₂O₅·8.3 MoO₃ (X=1–2) calcined in flowing nitrogen at 250–350 °C have revealed the exchange interaction of Cu²⁺ and V⁴⁺ ions that form a paramagnetic system.

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X(CuO) V₂O₅·8,3 MoO₃, X=1–2, , 250–350°C, Cu²⁺ V⁴⁺, .

     

The isoconversional method for determination of energy of activation at constant heating rates

The isoconversional method for the determination of energies of activation from the reciprocal temperature at which a fraction of conversion was reached in experiments at differing constant heating rates is reviewed and amplified. The error introduced into the calculation of activation energy by the use of a linear approximation of the logarithm of the temperature integral is discussed. Methods for the correction of this error are developed and a table of correction factors are given.

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Zusammenfassung Es wird eine Literaturübersicht über die und eine ausführliche Darstellung der Isokonversionsmethode zur Bestimmung von Aktivierungsenergien aus den Reziprokwerten derjenigen Temperaturen gegeben, bei denen ein bestimmter Konversionsgrad in Experimenten mit verschiedener Aufheizgeschwindigkeit erreicht wird. Der in die Berechnung der Aktivierungsenergie durch lineare NÄherung des Logarithmus des Temperaturintegrals eingehende Fehler wird diskutiert. Es werden Methoden zur Korrektur dieses Fehlers entwickelt und Korrekturfaktoren in Tabellenform angegeben.

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, . , . .

     

A rapid test for evaluating the degree of cure in CFRP composites

A noncontact optothermal method is described for possible application to routine industrial evaluation of the degree of cure in polymeric composites. The surface of the part is heated by a laser beam or other radiative source while its temperature evolution is continuously monitored with an infrared detector. A strong exothermal peak is observed when the material is partially or totally uncured. Changes in the signal shape related to variations of the part geometry or environmental conditions are minimized by a differential approach comparing subsequent heat cycles on the same area. Results obtained with cured or uncured graphite-epoxy prepreg sheets are presented.

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Zusammenfassung Es wird eine Nonkontaktmethode zur möglichen Anwendung für industrielle Routinebestimmungen des Vulkanisationsgrades von Polymergemischen beschrieben. Die Oberfläche der Probe wird durch einen Laserstrahl oder durch eine andere Strahlungsquelle erhitzt, wobei das Temperaturverhalten durch einen Infrarotmonitor kontinuierlich verfolgt wird. Ist das Metall partiell oder vollkommen vulkanisiert, kann man ein stark exothermes Signal beobachten. Durch Probengeometrie oder Umweltbedingungen verursachte Signalformänderungen werden durch eine Differentialnäherung mittels Vergleich aufeinanderfolgender Erhitzungszyclen an der gleichen Stelle minimal gehalten. Es werden einige Ergebnisse von vulkanisierten und unvulkanisierten Graphit-Epoxy Blättchen dargelegt.

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- . - , . , , . , , . , - .

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One part appeared in NDT Comm., 3 (1987) 1.     

Dioxygen evolution from aqueous acid solutions of ruthenium complexes with nitrogen-containing ligands

Some peculiarities of reduction of one-electron oxidants, Ru(bpy) ₃ ³⁺ and Ru(bpy)₂(py) ₂ ³⁺ , in the absence of catalysts (when oxidation of the oxidant's ligands occurs) and in their presence (when also oxidation of water to dioxygen occurs) are discussed. Both oxidation reactions are thought to have a common intermediate.

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Ru(bpy) ₃ ³⁺ Ru(bpy)₂(py) ₂ ³⁺ ( -) ( ). , .

     

Some remarks about butene-1 transformations on NaHY zeolite

Comments are given on the paper Alternative Interpretation of Infrared Spectra of the Zeolite NaHY+Butene-1 System of Forster and Seelemann /2/. Our previous paper /1/ was partly revised but the usefulness of comprehensive studies by infrared and temperature-programmed desorption methods has been emphasized.

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: NaHY+-1. [2]. [1] , - .

     

Analysis of thermal desorption spectra of oxygen desorbed from rhodium

Thermal desorption spectra of oxygen desorbed from rhodium have been analyzed in terms of models accounting for the effect of lateral interactions between adsorbed particles and of their diffusion into the bulk of metal on the desorption kinetics of O₂. Complex configuration of these spectra is ascribed to the processes of formation/decomposition of surface Rh oxides and the diffusion of particles into the near-surface layers of metal and back to the surface.

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- , O₂ . - O₂ Rh - .

     

Kinetics and mechanism of the permanganate oxidation of trans-crotonic acid

The kinetics and intermediates of the permanganate oxidation of trans-crotonic acid have been investigated in the pH range of 0.5–5.0 using the stoppedflow technique. The formation of manganese(III) as a short-lived intermediate has been established. The reaction is first order with respect to both MnO ₄ ^– and crotonic acid (crotonate). The resolved rate constants at 25°C are 730 and 410 M^–1 sec^–1 for the acid and the anion, respectively. The reaction mechanism is discussed.

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pH=0,5–5,0, . (III) . MnO ₄ ^– , (). 25°C 730 410 M^{–1 –1} , . .

     

m-Xylene conversion over dealuminated Y zeolites studied by the pulse method

m-Xylene conversion was studied over dealuminated Y type zeolites in hydrogen forms, SiO₂ to Al₂O₃ ratios were varied from 4.86 to 12.95.

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- . SiO₂/Al₂O₃ 4,86 12,95.

     

Hydrogenation of xylenes over supported Pt catalysts. Influence of different variables on their catalytic activity

In this work we studied and compared the catalytic activity of various supported Pt systems on the gas-phase hydrogenation of o-, m- and p-xylene. We analyzed the influence of different catalyst preparation variables (solvent, precursor, salt, support and catalyst reduction temperature used) on the catalytic activity and selectivity towards the corresponding cis-and trans-dimethylcyclohexanes.

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- o-, m- -. (, , ) - -.

     

IR-spectroscopic studies of strength and concentration of acid centers on V2O5/Al2O3 catalysts

The strength of protonic sites and the concentration of acid centers in V₂O₅/Al₂O₃ catalysts have been estimated according to pyridine and ammonium adsorption.

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V₂O₅/Al₂O₃.

     

Thermal decomposition of the solvent-extracted chloro complexes of vanadium(IV) with trioctylamine and trioctylmethylammonium chloride

The complexes (R₃NHVO(OH)Cl₂)₂ and (R₃RNVO(OH)Cl₂)₂ prepared by drying in vacuo the organic solutions from the extraction into benzene of aqueous vanadyl chloride solution with trioctylamine (TOA, R₃N) and trioctylmethylammonium chloride (TOMAC, R₃RNCl), were studied by thermogravimetry and differential thermal analysis under an atmosphere of nitrogen, and the products of their thermal decomposition, such as volatile matter and residues, by gas chromatography. X-ray diffraction and infrared spectroscopy. It was found that the complexes with TOA and TOMAC thermally decompose to V₂O₃ at 200–300° by cracking of the compounds R₃NHVO(OH)Cl₂ and R₃RNVO(OH)Cl₂ formed via dissociation of the complexes at about 150°.

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Zusammenfassung Die Komplexe (R₃NHVO(OH)Cl₂)₂ und (R₃RNVO(OH)Cl₂)₂ wurden hergestellt, indem benzolische und wässrige Vanadylchlorid-Lösungen mit Trioctylamin (TOA, R₃N) und Trioctylmethylammoniumchlorid (TOMAC, R₃RNCl) extrahiert und die erhaltenen Lösungen im Vakuum eingedampft wurden. Die Komplexen wurden in Stickstoffatmosphäre mittels TG und DTA untersucht und die thermischen Zersetzungsprodukte, und zwar sowohl die flüchtigen Verbindungen als auch die Rückstände, gaschromatographisch bzw. röntgendiffraktometrisch und IR-spektroskopisch bestimmt. Es wurde festgestellt, daß die Komplexe mit TOA und TOMAC bei 150° in die Verbindungen R₃NHVO(OH)Cl₂ und R₃RNVO(OH)Cl₂ dissoziieren, die bei 200–300° thermisch zu V₂O₃ zersetzt werden.

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(R₃NHVO(OH)Cl₂)₂ (R₃RNVO(OH)Cl₂)₂ (R₃,) ( , R₃RNCl). , , . , 200–300° V₂₃ R₃NV()l₂ R₃RNVO(OH)Cl₂, 150°.

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We wish to thank the Koei Chemical Co. Ltd. for samples of TOA and TOMAC.     

Temperature programmed reduction and oxidation of Ir/Al2O3 catalysts

3 % Ir/Al₂O₃ catalysts have been studied by means of temperature programmed reduction and oxidation. With growing degree of metal oxidation (higher T_ox) reducibility of the catalysts at low temperatures decreases.

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3% Ir/Al₂O₃ . ( ) .

     

Oxidation of propylene to acrylic acid on a Fe?Mo?Bi oxide system

Data obtained in a flow reactor show that iron(III) molybdate doped by bismuth can oxidize propylene to acrylic acid directly in one step. Part of the catalyst works in a partially reduced form and in the preparation of the catalyst the surface acidity must be controlled.

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, , (III), , . .

     

Kinetics of Cr(VI) and V(V) oxidation of trans-stilbene and indene

Title reactions are acid catalyzed and strongly dependent on the permittivity of the medium. With Cr(VI) indene reacts faster than trans-stilbene, but with V(V), trans-stilbene reacts faster than indene. The mechanism is discussed.

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. Cr(VI) , -, V(V) - , . , .

     

Thermal and some other properties of the complexes crystallizing from the system Ni(II)-en-[Ni(CN)4]2−-H2O

Seven complex compounds exhibiting the compositions Ni(en)₃Ni(CN)₄·H₂O (I), Ni(en)₃Ni(CN)₄ (II),-Ni(en)₂Ni(CN)₄ (III), Ni(en)Ni(CN)₄·2H₂O (IV), Ni(en)Ni(CN)₄ (V), Ni(en)₂Ni(CN)₄ · 2.5H₂O (VI) and-Ni(en)₂Ni(CN)₄ (VII) were prepared from the system Ni-en-[Ni(CN)₄]^2–-H₂O. These compounds were examined by the methods of infrared spectroscopy, X-ray powder diffractometry, UV-VIS reflectance spectroscopy, and also by the measurement of magnetic moments. The thermal stability, the stoichiometry of thermal decomposition and the mutual transformations were investigated with a derivatograph. The reactions proceeding according to the following schemes were observed if the system was heated to appropriate temperature: (I)(II)(III)(V)(IV) and (VI)(VII)(III)(V)(IV) Process (VII)(III) represents isomerization. The reversibility of the process (V)(IV) is due to the high hygroscopicity of the anhydrous complex. The changes in structure in the course of the individual processes are discussed.

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Zusammenfassung Aus einem System Ni-en-[Ni(CN)₄]^2–-H₂O wurden sieben Komplexe der Formeln Ni(en)₃Ni(CN)₄·H₂O (I), Ni(en)₃Ni(CN)₄ (II),-Ni(en)₂Ni(CN)₄ (III), Ni(en)Ni(CN)₄·2H₂O (IV), Ni(en)Ni(CN)₄ (V), Ni(en)₂Ni(CN)₄ · 2.5H₂O (VI) und-Ni(en)₂Ni(CN)₄ (VII) hergestellt. Diese Verbindungen wurden mittels IR-Spektroskopie, Röntgenpulverdiffraktometrie, UV-Reflexionsspektroskopie und durch Messungen des magnetischen Momentes untersucht. Die Wärmestabilität, die Stöchiometrie des thermischen Zerfalles und die gegenseitigen Umwandlungen wurden mittels eines Derivatographen untersucht. Wird das System auf geeignete Temperaturen erhitzt, kann der Reaktionsverlauf durch folgendes Schema dargestellt werden: (I)(II)(III)(V)(IV) und (VI)(VII)(III)(V)(IV).Der Prozeß (VII)(III) verkörpert eine Isomerisierung. Die Umkehrbarkeit von Prozeß (V)(IV) ist auf die ausgeprägten Hygroskopieeigenschaften des wasserfreien Komplexes zurückzuführen. Es werden die im Ablaufe der einzelnen Prozesse vorgehenden Strukturveränderungen besprochen.

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Ni- -[No(N)]² -₂ Ni(en)₃Ni(CN)₄ · ₂ (I), Ni(en)₃Ni(CN)₄ (II),-Ni(en)₂Ni(CN)₄ (III), Ni(en)Ni(CN)₄-2H₂O (IV), Ni(en)Ni(CN)₄ (V), Ni(en)₂Ni(CN)₄ · 2,5H₂O (VI) -Ni(en)₂Ni(CN)₄ (VII). , , - , . , . (I)(II)(III)(V)(IV) (VI)(VII)(III)(V)(IV). (VII)(III) . (V)(IV) . .