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.     

Decomposition of isopropanol on V2O5 of different grain morphology and its relation to o-xylene oxidation catalysts

Decompositon of isopropanol has been studied on V₂O₅ samples of different morphology. It has been shown that the selectivity to acetone increases with the increase in the fraction of (010) plane of V₂O₅ on the sample surface, whereas the selectivity to propene decreases. The results are compared with previous data of o-xylene oxidation on the same samples and discussed in terms of the model of V₂O₅ surface [7].

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V₂O₅ . , (010) V₂O₅ , . - V₂O₅.

     

Acetylene adsorption on a clean iridium surface

The interaction of C₂H₂ with a polycrystalline iridium surface at 140 KT500 K has been studied by AES, XPS and UPS. A model of the bonding between C₂H₂ and Ir by the 1 orbitals of the hydrocarbon is proposed. The more pronounced energy splitting between the orbitals of acetylene during adsorption compared to that in the gas phase is ascribed to deformation of the acetylene molecule.

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C₂H₂ . 140 KT500 K AES, XPS UPS. C₂H₂ Ir 1- . - , , .

     

Radiolysis of nitrous oxide adsorbed on alumina ionic mechanism of radiolysis of nitrous oxide on alumina with small surface areas

A mechanism is proposed for the radiolysis of adsorbed N₂O describing the experimental dependences of the radiation-chemical yields of O _st ^– and N₂ on N₂O coverages.

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N₂O, - O _st ^– N₂ N₂O.

     

A thermal synthesis of a new tin(IV) dithiocarbamate

A new tin dithiocarbamate containing sulphur bridges, di--sulphidobis [bis(N,N-diethyldithiocarbamato)tin(IV)], has been isolated from the thermal decomposition of tetrakis(N,N-diethyldithiocarbamato)tin(IV). A dimeric structure is proposed on the basis of results from mass spectrometry, infrared spectroscopy, thermal analysis and vapour pressure osmometry.

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Zusammenfassung Ein neues, Schwefelbrücken enthaltendes Zinn-Dithiocarbamat, Di--sulfidobis[bis(N,N-diäthyldithiocarbamato)Zinn(IV)], wurde bei der Zersetzung von Tetrakis(N,N-diäthyl-dithiocarbamato)Zinn(IV) isoliert. Aufgrund der Ergebnisse der Massenspektrometrie, der Infrarotspektroskopie, der Thermoanalyse und der Dampfdruck-Osmometrie wird eine Dimerstruktur vorgeschlagen.

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Résumé Un nouveau dithiocarbamate d'étain contenant des ponts de soufre, le di--sulfidobis[bis(N,N-diéthyl-dithiocarbamato)é tain(IV)], a été isolé lors de la décomposition thermique du tétrakis(N,N-diethyl-dithiocarbamato) étain(IV). Une structure dimère est proposéeà partir des résultats obtenus par spectrométrie de masse, spectroscopie infrarouge, analyse thermique et osmométrie sous pression de vapeur.

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—-- [/N,N- (/IV)], [/N,N- (/IV)], , (N,N- ) (IV). - , , .

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The authors gratefully acknowledge the assistance given by Dr. A. G. Wedd with the vacuum sublimation technique. One of us, G. K. B., is grateful for a research scholarship provided by La Trobe University.     

Oxidative dehydrogenation of n-butane, III. Kinetic and catalytic activity of ferric oxide

Catalytic activity of ferric oxide was evaluated in the oxidative dehydrogenation of n-butane. The apparent activation energy determined in the kinetic region was 37.7 kcal/mol. The activity of this oxide was undetectable up to 430°C. Reaction product distributions are shown as functions of temperature in the range of 430–650°C.

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(III) -. 37,7 /. 430°C. 430–650°C.

     

Oscillating autoxidation reaction of p-xylene in the liquid phase, catalyzed by metal oxides

Oscillatory reaction was observed during liquid-phase oxidation of p-xylene in the presence of certain transition metal oxides as catalysts. Experimental conditions under which oscillations occur and parameters influencing this behavior are described.

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, , , . - .

     

Oxidizing supported reagents, III. Oxidation of alcohols by new supported K2Cr2O7 reagents

Several new supported K₂Cr₂O₇ reagents are used in the oxidation of secondary alcohols. The influence of the number of active sites and the nature of solid support on the yield is discussed. The influence of the structure of alcohol on the yield of ketone is analyzed.

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K₂Cr₂O₇ . . .

     

Gas-phase hydroformylation of propylene on Ru/SiO2 catalysts

Ru/SiO₂ catalysts prepared by reduction of supported RuCl₃·xH₂O are active in gas-phase hydroformylation of propylene at low pressure (ca. 0.3 MPa) of H₂+CO+C₃H₆ mixtured and show unexpectedly high selectivity towards unbranched oxo-products. Data concerning the effect of electronic state and dispersity of Ru on their catalytic behavior have been obtained.

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Ru/SiO₂, RuCl₃·xH₂O, (0,3 ) - . .

     

Oxidative dehydrogenation (OXD) of n-butane I. Activity of natural quartz II. Kinetic and catalytic activity of nickel oxides

The oxidative dehydrogenation of n-butane on nickel oxide catalysts and on natural quartz, used as catalysts diluent, were studied. It is assumed that oxygen ions from the oxide lattice participate in the initial step of the reaction.

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- , . , .

     

V2O5/TiO2 oxidation catalysts, IV. Adsorption of acrolein on sodium-containing systems

Adsorption of acrolein on vanadia/titania catalysts fits a polymerization kinetics if Na–V compounds are not present or the vanadium content is lower than that corresponding to formation of a monolayer of vanadia on the titania support.

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, Na–V .

     

Oxidation of triethylamine by molecular oxygen catalyzed by Ru(III)-ion

The kinetics of Ru(III) catalyzed oxidation of triethylamine by molecular oxygen has been investigated in the pH range 1.5 to 2.5 at 35°C and I=0.1 M KCl. The reaction is first order with respect to substrate, catalyst and molecular oxygen concentrations. The rate of the reaction increases with the increase of pH from 1.5 to 2.5 and then there is a slight decrease in the rate above pH 2.5. Based on the kinetic data, a mechanism for the catalytic oxidation of triethylamine is proposed. The major products in the oxidation of triethylamine are the N-oxide, diethylamine and acetaldehyde.

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, Ru(III), pH=1,5+2,5 35°C I=0,1M KCl. , . pH 1,5 2,5, pH 2,5. , . N-, .

     

Isomerization, dehydrogenation and cracking of methylcyclohexane over HNaY zeolites

On HNaY zeolites the fractions of acid sites which are active for cracking, isomerization and dehydrogenation of methylcyclohexane do not increase linearly with increasing degree of exchange. Isomerization and dehydrogenation seem to involve a similar activated complex, while cracking proceeds through a different one and requires stronger acid sites. Activation energies are independent of exchange degree.

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HNaY, , . , . .

     

Reduction behavior of Cu?SiO2 catalyst prepared by ion exchange for selective dehydrogenation to produce methyl formate from methanol

Reducibility of Cu–SiO₂ catalyst prepared by ion exchange method, being effective for selective dehydrogenation to produce methyl formate from methanol at lower temperatures, has been studied by a TPR technique. The results suggest that easier reduction leads to an increase of dispersity of Cu particles.

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, - , , . , , Cu.

     

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.     

The compensation effect: A fact or a fiction

In this article, the facts and fictions surrounding the compensation effect is explored. False compensation effect occurs mainly due to: propagation of computational and experimental errors resulting in inaccurate estimates of the Arrhenius parameters; and, the natural compensation between InA andE. Since Arrhenius parameters are sensitive to errors in temperature; the errors due to uncertainty in temperature should be minimized to eliminate false compensation effect. Increasing the experimental temperature range is helpful in minimizing errors due to uncertainty in temperature. A point of concurrence in a plot of Ink and 1/T establishes the occurrence of true compensation effect. True compensation effect has been shown to be a useful tool in chemical research for: identifying the governing reaction mechanism; predicting the effects of various reaction parameters; and, correlating and reducing experimental data.

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Zusammenfassung In dieser Mitteilung werden Fakten und Vorstellungen betreffs des Kompensationseffektes untersucht. Falsche Kompensationseffekte werden hauptsächlich verursacht durch: eine ungenaue Ermittlung der Arrheniusparameter durch die Fortpflanzung von rechnerischen und experimentellen Fehlern sowie dem natürlichen Kompensationseffektes zwischen InA undE. Das Arrheniusparameter gegenüber Fehler im Temperaturwert sehr empfindlich sind, sollten Temperaturungenäuigkeitsfehler zur Vermeidung eines falschen Kompensationseffektes minimalisiert werden. Zur Verminderung der aus der Temperaturungenauigkeit resultierenden Fehler ist es von Nutzen, den Temperaturbereich des Experimentes zu erweitern. Ein wahrer Kompensationseffekt wird durch einen Schnittpunkt in einem Ink-1/T Diagramm angezeigt. Es wird gezeigt, daß der wahre Kompensationseffekt ein nutzvolles Mittel in der chemischen Forschung darstellt: zur Feststellung des dominierenden Reaktionsmechanismus, zur Vorhersage der einflüsse verschiedener Reaktionsparameter und zur Aufarbeitung und Schlußfolgerung von bzw. aus experimentellen Daten.

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, . , , lnA E. , , . . Ink-1/T . , , , .

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The author would like to thank the reviewer for his constructive criticisms.     

A thermogravimetric study of the solid-state reaction between alumina and strontium carbonate

The kinetics of the solid-state reaction between alumina and strontium carbonate were studied by thermogravimetry. The effects of the structure ( or) and/or doping (with Li⁺ or Cd²⁺) of the alumina on the kinetics of the reaction were examined. The results obtained were correlated with the phase composition and structural changes, followed by a number of physicochemical analyses (DTA, XRA and IRA) throughout the course of the reaction.

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Zusammenfassung Die Kinetik der Festkörperreaktion zwischen Aluminiumoxid und Strontium-carbonat wurde thermogravimetrisch untersucht. Die Effekte der Struktur ( und) und/oder des Dopens des Aluminiumoxids (mit Li⁺ oder Cd²⁺) auf die Kinetik der Reaktion wurde untersucht. Die erhaltenen Ergebnisse wurden mit der Phasenzusammensetzung und mit durch physikalisch-chemische Analysenverfahren (DTA, XRA und IRA) während des Reaktionsverlaufs verfolgten strukturellen Veränderungen in Beziehung gebracht.

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. ( ) Li⁺ Cd²⁺ . , , - .

     

Kinetic equation of heterogeneous catalytic isotope exchange

A kinetic equation is derived for the bimolecular isotope exchange reaction between AX _n ^* and BX _m ^o , all atoms of element X in each molecule being equivalent. The equation can be generalized for homogeneous and heterogeneous catalytic isotope exchange.

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, AX _n ^* BX _m ^o , X . , - .

     

A thermoanalytical study on some compounds of Zr(IV) with azopyrazolonic derivatives

Thermoanalytical data on six reagents and on their compounds with Zr(IV) are reported. Except for H acid, all reagents were azopyrazolonic derivatives obtained by synthesis. The purpose of this study was to obtain data on the thermal stabilities of the reagents and their zirconium compounds, and to establish the reagent: zirconium: water combination ratio.

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Zusammenfassung Thermoanalytische Daten von 6 Reagenzien und deren Verbindungen mit Zr(IV) werden mitgeteilt. Außer H-Säure waren alle Reagenzien durch Synthese erhaltene Azopyrazolon-Derivate. Zweck der Untersuchung war, Daten über die thermische Stabilität dieser Reagenzien und ihrer Zirkonverbindungen zu erhalten und das Verhältnis Reagens: Zirkon: Wasser festzustellen.

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. , , - . , : : .