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1.
Hydrogenolysis of ethane, n-hexane and cyclohexane has been studied on nickel-kieselguhr catalysts modified by organic and inorganic compounds of tin. Tin additives decrease nickel reactivity with respect to C–C dissociation, which is ascribed to the formation of surface intermetallides on the catalyst.
, - - , . . C–C .
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2.
The kinetics of isothermal-isobaric dehydration of Li5P3O10·5H2O in vacuum (p=10–1 hPa) and in water vapour atmosphere ( =23·hPa) was investigated by TG in the temperature range 40–140°. It was shown that the initial non-degradation removal of 1/10 of the crystal water, the rate of which is sensitive to , proceeds according to the laws of reversible topochemical reactions. In the next, irreversible degradation stage, where the bulk of the crystal water is removed, the kinetic characteristics of the process and the DSC effects exhibit a low sensitivity to the water vapour pressure. The peculiarities of Li5P3O10·5H2O dehydration were considered in comparison with the thermal behaviour of Na5P3O10·6H2O and K5P3O10·4H2O.
Zusammenfassung Die Kinetik der isotherm-isobaren Dehydratisierung von Li5P3O10·5H2O in Vakuum (p=10–4 hPa) und in Wasserdampfatmosphäre ( =23 hPa) wurde durch TG im Temperaturbereich von 40–140° untersucht. Es wurde gezeigt, daß die anfängliche, noch keine Zersetzung zur Folge habende Eliminierung von 1/10 des Kristallwassers, deren Geschwindigkeit von abhängt, nach den Gesetzen der reversiblen topochemischen Reaktionen abläuft. Im nächsten irreversiblen Zersetzungsschritt, in dem die Hauptmenge des Kristallwassers austritt, sind die kinetischen Kennwerte des Prozesses und die DSC-Effekte nur wenig vom Wasserdampfdruck abhängig. Die Besonderheiten der Dehydratisierung von Li5P3O10·5H2O werden im Vergleich mit dem thermischen Verhalten von Na5P3O10·6H2O und K5P3O10·4H2O erörtert.

40–140° - Li5P3O10 · 52 (=10–4 ) (=23 ). , 1/10 , . , - . L5310·52 Na5P3O10·6H2O K5310·42.
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3.
Reactivity and rate constants in reactions between peroxyl radicals of ethylene glycol diacetate and aromatic nitrons have been investigated.
.
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4.
It has been established that the interaction of (C6H5CH2)3Ti with butadiene does not change the parameters of ESR spectra. Only the hydrodynamic radius of this complex increases.
, (C6H5CH2)3Ti . .
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5.
Zinc exchanged zeolite X was found to catalyze effectively the dehydrosulfurization of ethanethiol. The catalytic activity correlated linearly with the degree of ion exchange and increased with the reaction temperature. The role of zinc cations in the reaction examined is discussed and suggestions concerning the reaction mechanism are put forward.
X, Zn, . . .
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6.
It has been known from the very beginning of the thermal analysis that the transport processes can significantly influence the thermoanalytical results. In this paper, three characteristic examples are given to show that this problem is more complex and arises more frequently than it is generally believed. The studied reactions are the carbon monoxide evolution from calcium oxalate, the thermal degradation of polytetrafluoroethylene, and the thermal decomposition of azodicarbonamide. TG and DSC experiments were carried out with sample masses varying between 0.05 and 8 mg. The necessity of the development of new kinetic models is concluded.
Zusammenfassung Seit den Anfängen der Thermoanalyse ist bekannt, dass Transportprozesse die thermoanalytischen Ergebnisse weitgehend beeinflussen können. Es werden hier drei Beispiele beschrieben, die zeigen, dass dieses Problem weitauf komplizierter ist und häufiger auftritt als allgemein angenommen wird. Die untersuchten Reaktionen sind die Kohlenmonoxidabspaltung aus Calziumoxalat, die thermische Zersetzung von Polytetrafluoräthylen und der thermische Zerfall von Azodicarbonamid. Die TG- und DSC- Untersuchungen wurden mit Probenmassen zwischen 0.05 und 8 mg durchgeführt. Es wird auf die Notwendigkeit der Entwicklung neuer kinetischer Modelle geschlossen.

, . , , . , . , 0,05 8 . .
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7.
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.
- , O2 . - O2 Rh - .
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8.
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.
- o-, m- -. (, , ) - -.
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9.
The catalytic properties and phase composition of the silica-supported vanadium-molybdenum oxide system have been studied in acrolein oxidation. The active component of the catalyst is the compound VMo3O11+x, whose maximum content is observed in the compositions range of 10–15 mol.% V2O5 –90–95 mol.% MoO3.
, SiO2. VMo3O11+x, 10–15 .% V2O5÷90–85 .% MoO3.
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10.
    
The activation energies of addition to ethene increase in the sequence of CH 3 \ , C2H5 \, 2-C3H7 \, CH2=CHH2 andtert-C4H9 radicals. The calculations support the correlation between H A and rHO and the Hammond postulate in alkyl and allyl radical additions and in the -bond scissions of the radicals studied.
: CH 3 \ , C2H 5 \ , 2-C3H 7 \ , CH2=CHCH 2 \ .-C4H 9 \ . H A rHO - .
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11.
3 % Ir/Al2O3 catalysts have been studied by means of temperature programmed reduction and oxidation. With growing degree of metal oxidation (higher Tox) reducibility of the catalysts at low temperatures decreases.
3% Ir/Al2O3 . ( ) .
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12.
In the analysis of the reaction between dissolving hydrogen and aqueous alkali hydroxide solutions the interaction of hydrogen with the molecular ion (H3O2) should be studied. This interaction is analyzed by the interacting bonds method. The activation energy (Ea) is estimated.
, (H3O2). . (Ea).
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13.
Studies of the phase composition and catalytic properties of several complex oxide catalysts for oxidative ammonolysis of propane indicate that the active phases of these catalysts are antimonates of the respective metals. Phosphorus and tungsten additives to the catalysts promote the formation of such phase compositions, i.e. the formation of antimonates and the binding of excess antimony oxide.
. , ; , .
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14.
Catalytic preparation of diacetone alcohol from acetone was studied using strong basic ion exchangers as catalysts. A continuous process was carried out in an enlarged laboratory set-up with controlled flow rate. Experiments were performed with respect to experiment duration, temperature, flow rate, catalyst porosity and catalyst-acetone ratio. The quantity of DAA was determined by gas chromatography. The effects of temperature, catalyst porosity and catalyst-acetone ratio on the reaction course were significant in comparison with other parameters examined. An exponential dependence of C/A ratio on DAA yield was found.
() , . . , , , /. . , / (/) . - /.
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15.
The preparation of vanadium-phosphorus catalysts is described, showing the considerable influence of phosphorus on the concentration of V4+ ions. The oxidation properties were studied by chemical analysis and electron spin resonance. Moreover, ESR spectra show a strong influence of moisture on the structure of the catalysts.
- , V+4. , . , , .
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16.
It is shown that unlike thermal pyrolysis, the rate of catalytic pyrolysis is greatly affected by dilution of hydrocarbons with inert gases. The nature of this effect has been analyzed.
, . .
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17.
The effect of two commercially available metal oxide curing agents, PbO2 and MnO2, on the cure time, kinetic parameters and ultimate tensile strength of the polysulphide polymer was investigated. The kinetic parameters for the thermal decomposition of the two systems were evaluated from their TG data. Both the energy of activation and pre-exponential factor showed a systematic increase with increase in cure and levelled off after the reaction. The cure time was also followed by determining the mechanical properties of the samples at regular intervals. The ultimate tensile strength values and the kinetic parameters follow similar trend with respect to the cure time. The kinetic parameters and the ultimate tensile strength for the PbO2 cured polysulphide system were on the higher side.
Zusammenfassung Es wurde der Einfluß von zwei im Handel erhältlichen Metalloxidhärtemitteln. PbO2 und MnO2, auf die Aushärtungszeit, die kinetischen Parameter und die Zugfestigkeit von Polysulfidpolymeren untersucht. Die kinetischen Parameter für die thermische Zersetzung der zwei Systeme wurden aus deren TG-Daten ermittelt. Sowohl die Aktivierungsenergie als auch der präexponentielle Faktor wachsen mit fortschreitender Aushärtung ständig an und erreichen nach Verlauf der Reaktion einen konstanten Wert. In gleichmäßigen Zeitabschnitten wurde die Aushärtungszeit auch durch Bestimmen der mechanischen Eigenschaften der Proben verfolgt. In Bezug auf die Aushärtungszeit zeigen die Zugfestigkeit und die kinetischen Parameter einen ähnlichen Verlauf. Die kinetischen Parameter und die Zugfestigkeit von mit PbO2 gehärteten Polysulfidsystemen zeigen bessere Werte.

, , , . , . . , . , . , , .


We thank Dr. R. Ramaswamy for supplying the resin and Dr. K. V. C. Rao and Director, VSSC for the kind permission to publish this work.  相似文献   

18.
The effect of the composition of the reaction medium on the rate of aniline oxidation to p-aminophenol by hydrogen peroxide on hemin immobilized on -propylimidazole-modified silica has been studied. Organic solvent additives (alcohols, esters and nitriles) are shown to increase the reaction rate. The observed effect is attributed to the decrease of the medium dielectric constant.
- , , --. , (, , ) . .
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19.
Oxidative coupling of alkylbenzenes (benzene, toluene, o-xylene, durene) is shown to proceed in the presence of palladium salts and heteropolyacids under the action of oxygen with a high yield of diaryls. The addition of mercury salts and variation of the solvent affect the reaction rate and isomer composition of the products.
, (, , -, ) . .
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20.
In terms of a unitary approach, the ability of complexes, clusters and metals of transition and nontransition elements for covalent interaction with reagents has been analyzed. the requirements for the catalysts to be efficient in the covalent activation of substrates have been formulated.
, . .
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