Reactivity of oxidized substances and its correlation with catalyst properties in deep oxidation reactions

In terms of the donor-acceptor interaction concept /1/ the relative reactivity (RR) of organic and inorganic compounds and its correlation with catalyst properties in deep oxidation reactions are treated. RR and relative activity of the catalysts are shown to change depending on the predominant character (acceptor or donor) of reactant-catalyst interaction.

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- /1/ (OPC) . , OPC .

     

Kinetic equations of isotope transfer by elementary reaction

On the basis of matrices of transfer of atoms kinetic equations of isotope transfer between the components participating in elementary reactions have been derived.

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, .

     

Influence of sodium salt addition on the morphological and catalytic properties (ethane hydrogenolysis) of aluminasupported cobalt

NaNO₃ addition to Co/Al₂O₃ results in an increase in the reducibility, in a smaller dispersity of the metal and in a decrease in the ethane hydrogenolysis rate due to a decorative effect.

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NaNO₃ Co/Al₂O₃ ,

     

Effects of tempering time and tempering temperature of caustic mercerization on the spectral and electrical properties of Egyptian cotton fibres

Several samples of Egyptian cotton fabric strips were subjected to various caustic mercerization conditions, varying in temperature and time. On these samples extensive measurements were undertaken, comprising X-ray diffraction, IR absorption spectra and the temperature-dependence of DC-electric conductivity.The phase constitution, % crystallinity, IR band assignment, activation energies for conduction and energy gap were evaluated as a function of caustic mercerization. The results obtained were correlated and discussed in detail, leading to valuable information of use in the cotton fabric strip industries.

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Zusammenfassung Verschiedene Proben von ägyptischen Baumwollstreifen wurden unter verschiedenen Bedingungen (Temperatur, Zeit) einer Laugung unterworfen. Die gelaugten Proben wurden eingehend durch Röntgendiffraktometrie, IR-Absorptionsspektroskopie und Messungen der Temperaturabhängigkeit der elektrischen Gleichstromleitfähigkeit untersucht. Phasenstruktur, Kristallinität, Zuordnung der Banden, Aktivierungsenergien für die Leitfähigkeit und verbotene Bänder wurden in Abhängigkeit von der Laugung ermittelt. Die erhaltenen Ergebnisse wurden miteinander verglichen und in Einzelheiten diskutiert, wobei für die Baumwollverarbeitungsindustrie wertvolle und empfehlenswerte Informationen erhalten wurden.

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. , . , , , . , .

     

Reactivity of finely dispersed iron (III) oxides and oxide hydroxides in solid-state reactions

The kinetics of the reaction of-Fe₂O₃ (hematite) with K₂CO₃ was studied at 600–800 °C for hematite samples prepared in different ways. The results demonstrated that the hematite reactivity is not a simple function of the specific surface area (or particle size), but depends significantly on the sample preparation history, especially at lower reaction temperature. The effect of low-temperature sintering on the hematite reactivity is discussed.

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Zusammenfassung Die Kinetik der Reaktion unterschiedlich präparierter-Fe₂O₃- (Hämatit-) Proben mit K₂CO₃ bei 600–800 °C wurde untersucht. Die Ergebnisse zeigen, dass die Reaktivität des Hämatits keine einfache Funktion der spezifischen Oberfläche (bzw. Teilchengrösse) ist, sondern deutlich von der Vorgeschichte der Probe, insbesondere bei tieferer Temperatur, abhängt. Der Einfluss des Tieftemperatursinterns auf die Reaktivität des Hämatits wird diskutiert.

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600–800° (-₂₃) . , ( ), , , «» . .

     

Photocatalytic electron transfer across the membranes of lipid vesicles mediated by diglycylamide of mesoporphyrin-IX N-metylglycomate

A peculiarity of the photocatalytic action of porphyrin molecules with different localization inside lipid bilayers of lecithin vesicles has been studied. The influence of an electrostatic field in the lipid membrane on the efficiency of electron photocatalytic transfer across the membrane is discussed.

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, - . . .

     

Thermal decomposition of ammonium nitrate dispersed in a multicomponent nitrate system

To obtain the kinetic curves of thermal decomposition of ammonium nitrate occurring together with decomposition of metal nitrates contained in a mixture, the ammonia contents evolved from samples heated under thermoanalytical conditions were determined by the Kjeldahl method.

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Zusammenfassung Der aus unter thermoanalytischen -Bedingungen erhitzten Proben freigesetzte Ammoniakgehalt wird durch das Kjeldahlverfahren bestimmt, um die kinetischen Kurven der thermischen Zersetzung von Ammoniumnitrat zusammen mit der Zersetzung von Metallnitraten in Gemischen zu erhalten.

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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⁺. .

     

A thermal decomposition study of some nickel(II)thioureachloride complexes

TG/DTA and Thermal Degradation Mass spectrometry (TDMS) data are presented for a series of nickel(II)thiourea chloride complexes: NiL₄Cl₂:L=thiourea or methyl-, dimethyl-, tetramethyl-, di-n-butyl, naphthyl-, ethylene- or allylthiourea. Two different thermal decomposition mechanisms are proposed for these complexes, and it is apparent that the thermal decomposition mechanism adopted by a particular complex depends on the structure of the relevant thiourea ligand and not on the nature of the halide ligand or on the existence of geometrical isomerism for these complexes.

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Zusammenfassung Durch TG, DTA und thermodegradative Massenspektrometrie (TDMS) von Nickel(II)-thioharnstoff-chlorid-Komplexen, NiL₄Cl₂ (L=Thioharnstoff oder Methyl-, Dimethyl-, Tetramethyl-, Di-n-butyl-, Naphthyl-, Vinyl- oder Allylharnstoff), erhaltene Daten werden angegeben. Zwei verschiedene Mechanismen werden für die thermische Zersetzung vorgeschlagen. Es ist offensichtlich, daß der Mechanismus, nach der die thermische Zersetzung eines gegebenen Komplexes verläuft, von der Struktur des relevanten Thioharnstoffliganden und nicht von der Natur des Halidliganden oder vom Vorliegen einer geometrischen Isomerie abhängt.

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/ - NiL₄Cl₂, L= , -, -, -, ---, -, - . . , .

     

Methane synthesis from CO/H2O mixture on supported nickel catalysts, I. Influence of the support on the catalytic properties

The behavior of some supported Ni catalysts for methane synthesis from CO and steam in correlation with the specific metal-support interactions is discussed.

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CO . .

     

Basic condensation of triphenylsilane. II. Kinetics in anhydrous isopropanol and influence of silanol

Condensation of triphenylsilane with isopropanol in presence of isopropoxide has been studied in anhydrous medium and the activation parameters have been measured. Dehydration of the medium has been obtained by means of a pre-reaction of triphenylsilane with the residual water in the solvent. In this medium the reaction is extremely slow, moreover, it is inhibited by silanol whose effect would lower the actual catalyst concentration.

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. . , .

     

On the occurrence of competitive mechanisms in the transformation of butadiene into maleic anhydride with air on MoO3?TiO2 catalysts

Unusual variations of selectivity are observed in the catalytic oxidation of butadiene on MoO₃–TiO₂ catalysts. A maximum of selectivity in furan and maleic anhydride is obtained at 400°C, since the oxidation of crotonaldehyde, dihydrofuran and furan are selective at all temperatures. Competitive oxidation of furan and crotonaldehyde proved that the aldehyde cannot be the unique intermediate for furan and maleic anhydride formation. Two mechanisms, involving various adsorbed species of butadiene, occur depending on the temperature and explain the decrease of the selectivity below 400°C.

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MoO₃–TiO₂ . 400°C, , . , . , , , 400°C.

     

Retarded solid state reactions

Reconstructive phase transitions and formation or decomposition reactions in the solid state exhibit in DTA-measurements a more or less great hysteresis between the temperatures from heating and cooling curves; at worst the reaction can be suppressed completely. By e.m.f.vs. T-measurements in appropriate galvanic cells for solid electrolytes equilibrium temperatures in the case of such kinetic hindrance can be determined and additionally the existence of metastable states can be proved.

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Zusammenfassung Rekonstruktive Phasenumwandlungen sowie Bildungs- und Zersetzungsreaktionen im festen Zustand zeigen bei DTA-Messungen eine mehr oder minder große Hysteresis zwischen den aus Aufheiz- bzw. Abkühlkurven ermittelten Temperaturen; schlimmstenfalls kann die Festkörperreaktion völlig unterdrückt sein. Mißt man in geeigneten galvanischen Zellen für Festelektrolyte EMK-gegen-T-Kurven, so erhält man auch im Falle kinetischer Hemmungen Gleichgewichtstemperaturen und kann darüber hinaus das Vorliegen metastabiler Zustände nachweisen.

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, : . .

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We have to thank the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industry for supporting our work from the outset.     

Influence des traitements thermiques sur l'etablissement des equilibres dans le systeme binaire hydroxyde de lithium-hydroxyde de sodium

Résumé L'utilisation systématique de recuits, contrôlés par des examens radiocristallographiques à températures variables, a permis de faire disparaître les équilibres métastables qui se manifestent entre les hydroxydes de lithium et de sodium. Trois composés sont identifiés avec certitude: 2 LiOH · NaOH, LiOH · NaOH et LiOH · 2 NaOH. Le composé équimolaire est dimorphe, la variété haute température étant de symétrie cubique.

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The systematic use of annealing operations controlled by radiocrystallographic examinations at various temperatures permits the elimination of metastable equilibria which occur between lithium and sodium hydroxydes. Three compounds have been characterized with certainty 2 LiOH · NaOH, LiOH · NaOH and LiOH · 2 NaOH. The equimolar compound presents in two crystalline forms: the high-temperature variety crystallizes in the cubic system.

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Zusammenfassung Die systematische Anwendung von Prozessen der Wärmebehandlung, welche durch radiokristallographische Untersuchungen bei verschiedenen Temperaturen kontrolliert wurde, ermöglicht den Abbruch der zwischen dem Lithium- und Natriumhydroxid bestehenden metastabilen Gleichgewichte. Drei Verbindungen konnten mit Sicherheit charakterisiert werden: 2 LiOH · NaOH, LiOH · NaOH und LiOH · 2 NaOH. Die äquimolare Verbindung ist dimorph, wobei die bei höherer Temperatur stabile Art eine kubische Symmetrie besitzt.

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, , , . :2LiOH. NaOH, LiOH. NaOH LiOH. 2 NaOH. , .

     

Nature of the adsorption centers of oxide catalysts and the direction of propylene conversion

According to the analysis of spectral data on adsorbed propylene forms, an attempt has been made to establish a relationship between the nature of olefin adsorption center, the adsorbed form during precatalysis and the direction of conversion.

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, .

     

State of components in contact solutions based on Pd(II) salts and Fe(NO3)3 for ethylene oxidation to EGMA

Physico-chemical studies of contact solutions based on Pd(II) salts and Fe(NO₃)₃ for ethylene oxidation to EGMA have been carried out.

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- (II) .

     

Thermal studies on some complexes of Pd(II)

The formulae suggested for a series of complexes of Pd(II) with various amino acids have been verified by thermal methods using a derivatograph. A correlation of the obtained kinetic parameters with the structures suggested by electronic and IR spectra of the substances has been attempted.

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Zusammenfassung Es wurden Formeln für eine Serie von Komplexverbindungen des Pd(II) mit verschiedenen Aminosäuren vorgeschlagen und thermogravimetrisch bewiesen. Die Übereinstimmung zwischen den erhaltenen kinetischen Parametern und den durch ERS und Infrarotspektroskopie angedeuteten Strukturen wurde geprüft.

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Résumé On a vérifié par thermogravimétrie des formules brutes proposées pour les combinaisons complexes du Pd(II) avec divers acides aminés. On a examiné la correlation entre les paramètres cynétiques obtenus et les structures déduites des spectres IR et electroniques.

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ë , Pd(II) . , , .

     

Catalytic isomerization of phenylcyclohexane in the presence of aluminium chloride

Intermolecular migration accompanied by deuterium atom rearrangement between the cycloalkyl fragment carbon atoms has been found during the interaction of phenylcyclohexane-1d₁ in benzene-¹⁴C with aluminium chloride. Relative rates of these conversions have been estimated. The reaction mechanism is discussed.

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, -1d₁ -¹⁴C , . .

     

A metal reactor for the diaphragm method with chambers providing complete mixing

A new metal reactor with two chambers in which complete mixing of gases is achieved has been developed for use in the diaphragm method. This apparatus is suitable for the determination of the effective diffusion coefficient and its temperature dependence. It can also be used to determine the type of transport, the gas permeability coefficient and to investigate the macrokinetics of catalytic processes.

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. : ; ; .

     

Hydrocondensation of CO: Catalytic activity of modified iron-alumina catalysts

The activity of modified Fe/Al₂O₃ catalysts in the hydrocondensation of CO has been studied in terms of the selectivity for light olefins and of repartition of the hydrocarbon products.

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Fe/Al₂O₃ CO, .