Kinetics of the catalytic transformation of isobutene into methacrylonitrile with NO on supported nickel oxide aerogel

Kinetic studies of the nitroxidation of isobutene by NO show that the reaction follows a redox mechanism in the temperature range of 300–400°C. This mechanism implies an interaction between dehydrogenated isobutene -allyl radical and atomic nitrogen due to the decomposition of NO by the reduced catalyst, which is then reoxidized.

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NO , 300–400°C. - , NO , .

     

Liquid phase CO+H2 reactions in presence of ruthenium catalysts

Several effects on the hydrogenation of carbon monoxide in propanol in presence of ruthenium catalysts are examined. The homologation reaction is not observed, only propyl formate and propyl acetate are produced with any ruthenium catalyst. The pH-value is an important parameter: in acid media, the yield of propyl formate is noticeably increased indicating different catalytic active species. The addition of cesium salts is also benefitial for formate formation. This is not the case when water is associated with propanol as solvent. Finally, no ethylene glycol is detected. The process is found to be homogeneous and methanol seems to be the precursor of methyl formate.

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, . , . : , . . , . . , -, .

     

Synthesis gas reactions on Pd-catalysts

Reactions of synthesis gas (CO/H₂) have been followed on a number of Pd-metal and Pd-alloy catalysts. Formation of methanol is sensitive to the choice of the carrier, but as the literature (and some of the data presented) is indicating, it is not proportional to the Pd-metal surface area. Alloying with Ag does not suppress methane formation substantially. It has been inferred from these results that methane is formed, at least partially, from an oxygen containing intermediate and that Pd ions play a role in the formation of these intermediates.

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, -, CO/H₂, Pd . , , ( ), Pd. . , , - , , , Pd.

     

Catalyst deactivation in toluene steam dealkylation

Two deactivation factors of Rh/-Al₂O₃ catalysts in toluene steam dealkylation are examined: deactivation during working and sulfur poisoning. Onstream deactivation is only due to coke deposit. Specific activity per free exposed fraction of the metal is constant. Sulfur is a strong non-selective poison which may hinder coke formation.

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Rh/-Al₂O₃ : . . . , .

     

Kinetics of oxidation of water by Mn(IV) sulfate in acid media

Kinetics of the Mn(IV)Mn(III) transition in the oxidation of watet to O₂ was investigated at 60–100°C in 6–15 M H₂SO₄. The reaction is approximately 2-nd order in Mn(IV) concentration in the process of oxidation and 1-st order in initial Mn(IV) concentration. The kinetics is interpreted by the existence of dimeric forms Mn(IV)·Mn(IV), Mn(IV)·Mn(III) and Mn(III)·Mn(III). The suggested mechanism includes O₂ formation directly in the coordination sphere of the Mn(IV)·Mn(IV) dimer in a polyelectronic process.

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Mn (IV)»Mn (III) O₂ 60–100°C 6–15 M H₂SO₄. Mn (IV) I- Mn (IV). [Mn (IV)]₂; [Mn(III)]₂ Mn(IV)·Mn (III). , [Mn (IV)]₂

     

Unimolecular decomposition of CF3OF-calculation by reduced Kassel integral in factorized form

The fall-off curves were calculated for the unimolecular decomposition of the trifluoromethyl hypofluorite at 475.8, 496.9 and 507.3 K by means of the Reduced Kassel Integral in Factorized Form.

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475,8,496,9 507,3 .

     

Catalytic deamination on solid surfaces part 2.-Deamination of dicyclohexylamine on aluminium oxide

Deamination of dicyclohexylamine gives the same final products as those obtained from the respective primary amine on a similar surface. A theoretical rate equation derived permits the calculation of various rate constants from the experimental data. It is concluded that one of the intermediates formed from the two amines must be identical.

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, . . , , , .

     

Über die Strukturänderung der Söderberg-Anode im Laufe der Elektrolyse

Zusammenfassung Es wurde die Änderung der Struktur der Söderberg-Anode im Laufe der Elektrolyse mit Hilfe der thermischen und mikroskopischen Analyse untersucht. Die Anode wurde in 10 Teilen von oben bis zu ihrem Unterteil im Elektrolyt aufgeteilt und die Teile separat der Untersuchung unterworfen. Die Ergebnisse gaben ausreichende Informationen über die Bildung des Sekundärkokses und über die Ausbildung der Inhomogenität in der Länge der Anode.

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Transformation of the anode structure during the electrolysis process was studied by means of thermal analysis and microscopy. The DTA method was found to be a good complement to traditional microscopic analysis. The autors succeeded in differentiating the formation and development of a secondary coke structure. The secondary coke is formed over half the anode length in the direction of the melt.

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. , . . .

     

On the thermal analysis of mineral components in clays

The paper deals with the problem of the interactions of the mineral components in clay and argillite samples during the thermal analysis. It is shown that depending on the experimental conditions, the interaction of pyrite and carbonates may cause atypical course of DTA and TG curves. Also the common occurring of sylvine and halite shifts the temperature of their melting to a lower value and this phenomenon occurs in pure salts as well as in the great dilution to some percent in clays.

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Zusammenfassung Es wird über Zwischenreaktionen der mineralischen Komponenten von Ton und Argillit während der thermischen Analyse berichtet. Von den Versuchsbedingungen abhängend produzieren die Zwischenreaktionen von Pyrit und Karbonat DTA und TG Kurven deren Verlauf nicht charakteristisch ist. Das gemeinsame Vorkommen von Sylvin und Halit verschiebt ihren Schmelzpunkt in Richtung der niedrigen Temperaturen in reinen Salzen ebenso wie bei großer Verdünnung von einigen Prozenten in Ton.

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Résumé Les interactions des constituants minéraux des échantillons d'argile et d'argilite pendant l'analyse thermique ont été examinées. Suivant les conditions expérimentales, l'interaction de la pyrite et des carbonates peut provoquer un tracé des courbes ATD et ATG qui s'écarte de l'allure type. La présence simultanée de sylvine et d'halite produit un abaissement de leur point de fusion et ce phénomène apparaít aussi bien avec les sels purs qu'avec ceux fortement dilués, à raison de quelques pour cent, dans les argiles.

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

     

Catalytic oxidation of cycloalkane heteroanalogs as a way to polyfunctional compounds

Liquid phase oxidation of cycloalkane diheteroanalogs catalyzed by compounds of Cu²⁺, Ni²⁺, Co²⁺, Cr³⁺, Fe³⁺ has been studied. It has been established that these catalysts can be applied to intensify, oxidize and increase the selectivity of this process.

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: Cu², Ni²⁺, Co²⁺, Cr³⁺, Fe³⁺. .

     

The reaction between nitrous oxide and carbon monoxide over magnesium oxide

The title reaction was carried out with the help of the transient response method over MgO. It was concluded that no catalyst reduction occurred over this catalyst and the reaction proceeded through the reaction between adsorbed nitrous oxide and adsorbed carbon monoxide without participation of MgO oxygen.

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MgO. , - MgO.

     

Infrared spectra of nitric oxide adsorbed on photoreduced V/SiO2 catalyst

Studies of the IR spectra of surface species produced via NO adsorption on selectively photoreduced V/SiO₂ catalysts indicate that at low coverages NO is adsorbed on V³⁺ ions to form strongly bonded mononitrosyl species V³⁺...... NO. With increasing NO coverage, V³⁺ is oxidized to V⁴⁺, which is accompanied by the appearance of gaseous N₂O and weak adsorption of NO on V⁴⁺.

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- , NO V/SiO₂ . , V³⁺ NO V³⁺... NO. V³⁺ V⁴⁺, N₂O NO V⁴⁺.

     

On the thermal analysis of aliphatic carboxylic acids and their salts

The thermal behaviour of oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic and sebacic acid, and of their mono- and disodium salts and calcium salts has been studied by derivatography. Some of the acids were distilled off without decomposition, while the others were decomposed in accordance with the rule of Blanc.Up to 600°, the decomposition of the monosodium salts consists of two principal steps. The first process is the liberation or the decomposition of the acid formed from the salt, the second step the decomposition of the normal salt into sodium carbonate and organic molecules. This decomposition mechanism was verified also by tracer technique on compounds labelled with the¹⁴C isotope. With most of the compounds unable to form ketones, the decomposition of the normal salt yields a great variety of organic compounds. In the case of adipates and pimelates the formation of cyclanones predominates.

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Zusammenfassung Es wurde das thermische Verhalten von Oxalsäure, Malonsäure, Bernsteinsäure, Glutarsäure, Adipinsäure, Suberinsäure, Azelainsäure und Sebacinsäure, sowie ihrer Mono- und Dinatrium- und Calciumsalze derivatographisch untersucht. Einige dieser Säuren destillierten ohne Zersetzung, die übrigen zerlegten sich entsprechend dem Blancs'schen Gesetz.Die Zersetzung der Mononatriumsalze verlief bis 600° in zwei Stufen. In der ersten wurde die salzbildende Säure freigesetzt oder zersetzt, in der zweiten zersetzte sich das normale Salz in Natriumkarbonat und in organische Moleküle. Der Zersetzungsmechanismus wurde mit durch¹⁴C markierten Verbindungen kontrolliert. Bei der Zersetzung der normalen Salze und der Verbindungen, die unfähig sind Ketone zu bilden, entstehen mannigfaltige organische Verbindungen. Im Falle von Adipaten und Pimelinaten überwiegen Cyclanone.

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Résumé On a étudié par dérivatographie le comportement thermique des acides oxalique, malonique, succinique, glutarique, adipique, pimélique, subérique, azélaique et sébacique, et de leurs sels mono et disodiques et de calcium. Certains de ces acides distillent sans décomposition, alors que d'autres se décomposent suivant la loi de Blanc.La décomposition du sel monosodique se déroule en deux étapes jusqu'à 600°. Dans la première, l'acide formant le sel se dégage ou se désompose; dans la deuxième, le sel normal de sodium se décompose en donnant du carbonate de sodium et des molécules organiques. Le mécanisme de la décomposition a été vérifié à l'aide de combinaisons marquées par le¹⁴C.La décomposition des sels normaux et des combinaisons impropres à donner des cétones fournit une grand variété de composés organiques. Dans le cas des adipates et des pimélates, la formation de cyclanones prédomine.

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, , , , , - . , . 600° . , , — « » . , C¹⁴ . . .

     

Spectroscopic studies of the state of Cu2+ ions in Cu?Zn?Al oxide catalysts

ESR and electronic spectroscopy have reveled that in low-temperature ZnO the copper ions form Cu–O–Cu type cluster structures with highly covalent bonds and strong exchange interaction between the ions. The nearer environment of the Cu²⁺ ions is an octahedron with distortion towards square planar coordination.

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, ZnO Cu–O–Cu . Cu²⁺- , .

     

Kinetic conversion of complex hydrocarbon mixtures in reforming on platinum/alumina catalysts

General forms of the kinetic equations for the conversion of various hydrocarbons in reforming of multicomponent gasoline fractions on platinum/alumina catalysts have been confirmed experimentally by using a gradientless method.

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.

     

X-ray studies of ZSM-5 zeolites with framework cations of various sizes

From a comparison of the X-ray difractograms for various ZSM-5 zeolites the isomorphous substitution of framework Si⁴⁺ by large cations (Al³⁺, Ga³⁺, Fe³⁺) is suggested to be ordered as contrasted to the statistical substitution by small ones (B³⁺).

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ZSM-5 , Si⁴⁺ (Al³⁺, Ga³⁺, Fe³⁺) , (B³⁺).

     

Study of the interaction of atomic oxygen and nitrogen with ruthenium by the bond interaction method

The heats of atomically adsorbed oxygen and nitrogen on Ru(0001) and Ru(1010) planes have been calculated by the semiempirical bond interaction method. The calculations show that oxygen is strongly adsorbed on ruthenium, while molecular nitrogen cannot be chemisorbed on ruthenium.

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- (000I) (I0I0) . , Ru , .

     

Thermal behaviour of some new hydrazinium fluorometallates

Three new hydrazinium(1+) fluoro complexes, N₂H₅AsF₆, (N₂H₅)₂ZrF₆ and (N₂H₅)₂HfF₆, were prepared and characterized by means of chemical analysis, IR and Raman spectroscopy and X-ray powder diffraction. Study of their thermal behaviour via TG, DTG and DTA measurements showed that they decompose in stages; the decomposition of N₂H₅AsF₆ proceeded in two steps, through the intermediate NH₄AsF₆; (N₂H₅)₂ZrF₆. Decomposed in three steps, through (NH₄)₂ZrF₆ and NH₄ZrF₅. The thermal decomposition of (N₂H₅)₂HfF₆ is more complex; in the first step (NH₄)₂HfF₆ with some N₂H₅HfF₅ was obtained, and in the second NH₄HfF₅. The intermediates were identified by means of chemical analysis and vibrational spectroscopy.

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Zusammenfassung Die Hydrazinium(1+)-fluorokomplexe N₂H₅AsF₆, (N₂H₅)₂ZrF₆ und (N₂H₅)₂HfF₆ wurden dargestellt und durch chemische Analyse, IR- und Ramanspektren sowie Röntgenbeugungsdiagramme charakterisiert. Die Untersuchung ihres thermischen Verhaltens durch simultane TG-DTG-DTA-Messungen zeigte, dass sie sich schrittweise zersetzen: N₂H₅AsF₆ zersetzt sich in 2 Stufen mit NH₄AsF₆ als Zwischenprodukt; (N₂H₅)₂ZrF₆ zersetzt sich in 3 Stufen über (NH₄)₂ZrF₆ und NH₄ZrF₅. Die thermische Zersetzung von (N₂H₅)₂HfF₆ ist komplizierter, der erste Schritt liefert (NH₄)₂HfF₆ mit wenig N₂H₅HfF₅, der zweite NH₄HfF₅. Die Zwischenprodukte wurden durch chemische Analyse und Schwingungsspektroskopie identifiziert.

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N₂H₅AsF₆, (N₂H₅)₂ZrF₆ (N₂H₅)₂HfF₆, - , ., , . , N₂H₅AsF₆ NH₄AsF₆, (N₂H₅)₂ZrF₆ — (NH₄)₂ZrF₆ NH₄ZrF₅. (N₂H₅)₂HfF₆ : (NH₄)₂HfF₆ N₂H₅HfF₅, NH₄HfF₅. .

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We thank Miss B. Sedej for chemical analysis. The work was financed through the Research Community of Slovenia.     

Investigation of ethylene interaction with some oxidants in the presence of Pd2+ in acetic acid

The composition of products from the interaction of ethylene with some o oxidants, catalyzed by palladium acetate in acetic acid has been studied, An assumption is made on the possible reason for the influence of such oxidants on the selectivity of formation of ethylene glycol ethers.

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, , . .