Co-adsorption studies of ethene with isotopically labelled water and hydrogen on copper/silica

The coadsorption of ethene with isotopically labelled water and hydrogen has been studied at temperatures between 423 and 623 K in a flow system. Ethene exchange has been shown to be independent of hydrogenation. When water is presnet, hydrogenation is poisoned but exchange can occur.

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423–623 . . , .

     

Characterization of titania and zirconia supported molybdenum oxide catalysts by low temperature oxygen chemisorption

Low temperature oxygen chemisorption (LTOC) has been applied to characterize a series of TiO₂ and ZrO₂ supported Mo-oxide catalysts. The monolayer coverage of the surface is completed when the Mo loading reaches 6% and 4% on the TiO₂ and ZrO₂ supports, respectively. The results are explained with the help of a Patch model of the Mo-oxide phase.

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Mo- TiO₂ ZrO₂ . Mo TiO₂ ZrO₂ 6% 4%, . Patch Mo- .

     

Coupling of autocatalytic cycles as a possible explanation of chemical oscillators

A general type of oscillating chemical network is presented in which two autocatalytic chemical cycles are coupled by an OR branching, and the second cycle is broached. The results are compatible with the Lotka model and the results of Noszticzius et al. A similar model is proposed also for the Belousov-Zhabotinskii reaction.

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, «» . . -.

     

Study of thermal behaviour of some derivatives of triphenylamine,with a view to obtaining new stationary phases for gas chromatography

A study was carried out upon the thermal behaviour of eight derivatives of triphen-y l amine, i. e. trinitrotriphenylamine; triaminotriphenylamine; triaminotriphenylamine chlorhydrate, tetraphenylborate and picrate; and a trisazo derivative and its compound with Be(II) and U(VI). The aim of this study was to find compounds with satisfactory thermal stability for use as stationary phases in gas chromatography.

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Zusammenfassung Eine umfassende Untersuchung zum thermischen Verhalten von acht Triphenylaminderivaten, d. h. Trinitrotriphenylamin, Triaminotriphenylamin, Triaminotriphenylamin Chlorhydrat, Tetraphenylborat und Pikrat, sowie ein Trisazoderivat und seine Verbindungen mit Be(II) und U(VI) wurde durchgeführt. Der Zweck dieser Studie war Verbindungen befriedigender Thermostabilität zum Einsatz als stationäre Phasen in der Gaschromatographie zu finden.

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: , , -, , () U(VI). .

     

EPR study of the nature of active sites and the type of their deactivation in CO hydrogenation on (Ni+Ti)/SiO2 catalysts

As shown by EPR, upon supporting Ni(-C₃H₅)₂ on Ti/SiO₂, the Ni complex is coordinated to Ti³⁺ ions. Deactivation of (Ni+Ti)/SiO₂ catalysts so obtained during CO hydrogenation is due to the oxidation of Ti³⁺ ions and metallic nickel particles by reaction products.

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, Ni(-C₃H₅)₂ Ti/SiO₂ Ni Ti³⁺. , (Ni+Ti)/SiO₂ CO Ti³⁺ .

     

Compensation effect in solid-state reactions. Thermolysis of one substance under differing experimental conditions

The compensation effect (lgZ=aE+wb) appearing at the thermolysis of one substance under different experimental conditions is discussed. The compensation effect of one and the same substance has no other physical meaning except the simple confirmation of the analytical relationship between lgZ andE that follows from the Arrhenius equation, and of the impossibility to determineZ from any independent experiment. Values of the coefficienta can not be the measure of the ruptured bond strength.

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(lgZ=+b), . , lgZ E ( ) Z . a .

     

Study of nitric oxide interaction with the Pt(100) surface by electron energy loss spectroscopy

The adsorption and dissociation of nitric oxide on the Pt(100) surface have been studied using Electron Energy Loss Spectroscopy.

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Pt(100).

     

Role of strongly bound vanadia in V2O5/Al2O3 catalysts for selective catalytic reduction of nitric oxide by ammonia

V₂O₅/Al₂O₃ catalysts prepared by impregnation and by ammonia treatment of impregnated samples were tested for activity in the NO–NH₃ reaction. The ammonia treated samples, with higher proportions of strongly bound vanadia, were found to be comparable in activity to the impregnated catalysts and equally sensitive to the presence of oxygen.

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V₂O₅/Al₂O₃, , NO–NH₃. .

     

Some studies on thallium oxalates. XIII. Sodium bis-oxalatodiaquothallate(III) monohydrate

Sodium bis-oxalatodiaquothallate(III) monohydrate has been prepared and characterised by chemical, thermal, X-ray diffraction and infrared spectroscopic methods. Thermoanalytical studies indicated that the complex decomposes through the formation of a mixture of thallium(I) oxalate and sodium oxalate, the final product at 650° being a mixture of thallium(I) oxide, thallium(III) oxide and sodium carbonate.

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Zusammenfassung Natrium-bis-oxalatodiaquothallat(III)-Monohydrat wurde hergestellt und chemisch, thermoanalytisch, röntgendiffraktometrisch und infrarotspektroskopisch charakterisiert. Thermoanalytische Untersuchungen haben ergeben, daß sich der Komplex unter Bildung eines Gemisches von Thallium(I)- und Natriumoxalat als Zwischenprodukt zersetzt. Endprodukt der Zersetzung bei 650° ist ein Gemisch von Thallium(I)-oxid, Thallium(III)-oxid und Natriumcarbonat.

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, --- () . , . 650° - .

     

Cobalt complex with immobilized porphyrin in hydrazine oxidation

Porphyrin immobilized on silica and its complex with cobalt have been prepared and identified. Oxidation kinetics is described by the Michaelis-Menten equation.

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- . - --.

     

Catalytic effect of an organic redox-indicator on the oscillatory behavior of 5-sulfosalicylic acid in acidic bromate

The presence of an organic redox indicator, sodium 4-diphenylamine-4-sulfonate, instead of inorganic catalysts has been found to greatly enhance the oscillatory behavior of 5-sulfosalicylic acid in acidic bromate under optinum conditions and slow stirring (50 rpm).

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-, 4--4- , , 5- , (50 ./).

     

Thermal oscillations in the catalytic oxidation of methanol

In the methanol oxidation on a Pd/LiAl₅O₈ catalyst thermochemical oscillations of very high amplitude (up to 90 K) were detected. Their mean value and their frequency are oxygen flow rate dependent.

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Pd/LiAl₅O₈ ( 90 ). .

     

Pyrolysis of propane in the presence of hydrogen

The pyrolysis of propane in the presence of hydrogen, deuterium and argon was studied in the temperature range 890–1019 K. The acceleration of the reaction in the presence of hydrogen has been observed.

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, 890–1019 . .

     

The application of low temperature differential scanning calorimetry to polymer blend analysis

The temperature regions in which glass transitions (Tg's) occur for a series of blends of polybutadienes with natural rubber and two styrenebutadiene copolymers of different styrene contents have been studied by differential scanning calorimetry. The resulting DSC curves may be used to categorize the polybutadiene, determine the bound styrene content of the styrenebutadiene copolymer and quantify the polybutadiene content of the blends.

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Zusammenfassung Die Temperaturbereiche, in denen bei einer Reihe von Gemischen von Butadien mit natürlichem Kautschuk und bei zwei Styrol-Butadien-Kopolymeren mit verschiedenem Styrolgehalt Glastransformationen erfolgen, wurden mittels DSC untersucht. Die erhaltenen DSC-Kurven können zur Kategorisierung des Polybutadiens und zur Bestimmung des Gehalts an gebundenem Styrol in Styrol-Polybutadien-Kopolymeren und des Polybutadiengehalts der Gemische verwendet werden.

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(_g) - . , - .

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Thanks are due to the Board of MRPRA for permission to publish this paper.     

Effect of acio properties of the alumina surface on the formation of chlorides during its interaction with CCl4

IR spectroscopy was employed to study acid properties of a series of alumina samples different in the phase composition and in the porous structure. The comparison of the surface acidity with the data on the quantitative formation of Cl^– during the interaction of CCl₄ with alumina indicates that the extent of chlorination of the samples tends to increase with increasing the surface acidity.

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- , . Cl^– CCl₄ , .

     

Study on the thermal behaviours of homo- and copolymers of styrene,MA and AN by thermogravimetry

The thermal behaviours of polystyrene (PS), polymethylacrylate (PMA), polyacrylonitrile (PAN), polystyrene-co-methylacrylate [P(S: MA)](alternate and random), polystyrene-co-acrylonitrile [P(S: AN)] (alternate) and a terpolymer of styrene, methylacrylate and acrylonitrile [P(S: MA: AN)] are discussed on the basis of non-isothermal thermogravimetric studies. The thermal stabilities of the copolymers have been found to be intermediate between of those of the individual homopolymers. The stability of the [P(S: AN)] copolymer is higher than those of the individual homopolymers. The activation energy values are also in accordance with the thermal behaviours of these polymers.

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Zusammenfassung Basierend auf nicht-isotherme thermogravimetrische Untersuchungen wurde das thermische Verhalten von Polystyrol [PS], Polymethacrylat [PMA], Polyacrylnitril [PAN], Polystyrol-co-methacrylat [P(S: MA)] (alternierend und random), Polystyrolco-acrylnitril [P(S: AN)] (alternierend) sowie eines Mischpolymeren von Styrol, Methacrylat und Acrylnitril [P(S: MA: AN)] untersucht. Die thermische Stabilität der Kopolymeren liegt zwischen denen der individuellen Homopolymeren. Die thermische Stabilität des Kopolymeren [P(S: AN)] ist höher als die der individuellen Homopolymeren. Die Werte der Aktivierungsenergie sind ebenfalls in Übereinstimmung mit dem thermischen Verhalten dieser Polymere.

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

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Presented at the 3rd National Symposium on Thermal Analysis held at VSSC, Trivandrum (India), November, 1981     

Reactivity of alkylphenols in liquid phase catalytic hydrogenation

The rate of liquid-phase hydrogenation of monoalkylphenols without solvent and in the absence of rate control by hydrogen diffusion to the catalyst indicate that the alkylphenol reactivity and the selectivity depend on the position and size of the alkyl substituent, affecting the electronic state of the aromatic ring and the charge on the carbonyl carbon atom of the ketone intermediate.

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, . , , .

     

Li/MgO catalysts: II. A DTA and TG study of precursors

The thermal decomposition of precursors of Li/MgO catalysts prepared from different Mg and Li compounds is reported. Dehydration and dehydroxylation is observed in both cases, in addition to decomposition of LiNO₃, but not of Li₂CO₃. The properties of the solids are related to the melting and spreading of LiNO₃ or Li₂CO₃ before or after Mg(OH)₂ dehydroxylation.

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Li/MgO, Mg Li. LiNO₃, Li₂CO₃, . LiNO₃ Li₂CO₃ Mg(OH)₂.