On the deactivation of Fe2O3?MoO3/SiO2 catalysts in the oxidation of methanol to formaldehyde

The deactivation behavior of Fe₂O₃–MoO₃/SiO₂ catalysts with different Fe₂O₃+MoO₃ content in the oxidation of methanol to formaldehyde is investigated. A simplified reaction-deactivation kinetic model is presented and used to compare and discuss the different behaviors.

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Fe₂O₃–MoO₃/SiO₂ Fe₂O₃+MoO₃ . : -.

     

Contribution a l'etude des associations aminophenazone-uree aminophenazone-thiouree et aminophenazone-noxythioline

The phase diagrams for aminophenazone-urea (a), aminophenazone-thiourea (b) and aminophenazone-noxythioline (c), established by differential scanning calorimetry, transparency method and thermomicroscopy, revealed the presence of definite compounds (1–3). These compounds are formed during eutectic fusion for (a) and (c); the definite compound for (b) displays non-congruent fusion.

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Zusammenfassung Aus den durch DSC ermittelten Phasendiagrammen für Aminophenazon-Harnstoff (a), Aminophenazon-Thioharnstoff (b) und Aminophenazon-Noxythiolin (c) sowie durch die Transparenzmethode und Thermomikroskopie wurde die Existenz der definierten Verbindungen (1–3) nachgewiesen. Diese Verbindungen werden im Falle von (a) und (c) in eutektischen Schmelzen gebildet. Die definierte Verbindung für (b) schmilzt nicht-kongruent.

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

     

Relative enthalpies and related thermodynamic functions of some organic compounds by drop calorimetry

The values of thermodynamic functions of the following eight organic compounds under non-reacting conditions within the temperature range 298.15 – 550 K are given: N,N dimethylformamide, CHO · N(CH₃)₂; 4-nitro-1-chlorobenzene, Cl · C₆H₄ · NO₂; sodiump-nitrophenoxide, NO₂ · C₆H₄ · ONa; 1-methyl-2-pyrrolidone, 4,4-dinitrodiphenyl ether, (NO₂ · C₆H₄)₂O; 4,4-diaminodiphenyl ether, (NH₂ · C₆H₄)₂O; bis-(4-aminophenyl)methane, (NH₂ · C₆H₄)₂CH₂; bis(4-maleic acidimidphenyl)methane, The relative enthalpy was obtained from calorimetric data by drop calorimetry. The heat capacity and relative entropy are functions derived from the foregoing. The equations of the temperature variation of the relative enthalphy were obtained by computer processing of the calorimetric data by the least squares method. The parameters of solid-liquid transitions were determined from the discontinuity of the temperature variation of the relative enthalpy.

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Zusamenfassung Die Werte der thermodynamischen Funktionen folgender 8 organischer Verbindungen werden unter nicht-reagierenden Bedingungen im Temperaturbereich von 298.15 bis 550 K angegeben: Dimethylformamid, CHO · N(CH₃)₂;p-Nitrochlorbenzol, Cl · C₆H₄NO₂; Natrium-p-Nitrophenoxid, NO₂ · C₆H₄ONa; N-Methylpyrrolidon, 4-4-Dinitrodiphenyläther, (NO₂ · C₆H₄)₂O; 4-4-Diaminodiphenyläther, (NH₂C₆H₄)₂O; 4-- 4-Diaminodiphenylmethan, (NH₂ · C₆H₄)₂CH₂; 4-4-bis-Maleinimid-Diphenylmethan, Die relative Enthalpie wird aus kalorimetrischen Daten der Temperaturgefällekalorimetrie erhalten. Die Wärmekapazität und die relative Entropie sind Funktionen der erwähnten Werte. Die Gleichungen der Temperaturänderung der relativen Enthalpie wurden mittels Computerverarbeitung der kalorimetrischen Daten, mit der Methode der kleinsten Quadrate erhalten. Die Parameter der fest-flüssig Übergänge wurden an Hand der Diskontinuität der Temperaturänderung der relativen Enthalpie bestimmt.

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Résumé On donne les valeurs des fonctions thermodynamiques des 8 composés organiques suivants, en conditions non réactionnelles, dans l'intervalle de températures 298.15–550 K: diméthylformamide CHO · N(CH₃)₂,p-nitrochlorobenzène Cl · C₆H₄ · NO₂,p-nitrophé noxysodium NO₂ · C₆H₄ · ONa, N-méthylpyrrolidone dinitrodiphényl-4,4 éther (NO₂ · C₆H₄)₂O, diaminodiphényl-4,4 méthane (NH₂ ·H ₄CH₂, 4-4 bis maléinimide diphénylméthane L'enthalpie relative a été obtenue à partir de données calorimétriques fournies par un calorimètre à chute. La chaleur spécifique et l'entropie relative sont des fonction dérivées de la précédente. Les équations donnant la variation de l'enthalpie relative en fonction de la température sont obtenues par traitement des données calorimétriques sur ordinateur par la méthode des moindres carrés. Les paramètres des transitions solide-liquide ont été déterminés à partir de la discontinuité de la variation de l'enthalpie relative avec la température.

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, 298,15–550 , : — · N(CH₃)₂;- — l · ₆₄ · NO₂.- -NO₂·₆₄·ONa; N-—₃·N··₂·₂₂; 4,4- — (NO₂·₆₄)₂; 4,4- — (NH₂·₆₄)₂; 4,4- — (NH₂·₆₄)₂₂; 4,4-- —(₆₄.N. . :. )₂₂. . , . . - .

     

A variational formulation of the rate equations for closed chemical systems

This paper presents a variational formulation of the kinetic equations corresponding to a closed chemical system.

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, .

     

Some peculiarities of cyclohexane conversion on zeolite catalysts

Cyclohexane conversion on zeolite and zeolite-containing catalysts has been examined. The formation of cracking, isomerization and dehydrogenation products is suggested to follow two parallel independent mechanisms through different intermediate carbocations.

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. , .

     

Depolymerization kinetics of the polymer formed in the reaction of 1-bromobutane on unmodified alumina

The slow processes accompanying the reaction of 1-bromobutane on unmodified alumina have been studied. Butenes and octane are formed via depolymerization of a low polymeric complex formed from the reaction product. The activation energy for the formation of products from the polymer has been determined.

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, 1- . , , , , . .

     

Competitive hydrogenation of 2-methyl-3-butene-2-ol and 1-hexene on a platinum catalyst modified by amines

The effect of the amount of diethylamine and triethylamine on the degree of poisoning of a hydrogenation catalyst 10% Pt on silica gel was examined. The dependence of the selectivity of competitive catalytic hydrogenation of 2-methyl-3-butene-2-ol and 1-hexene in methanol and cyclohexane on the degree of poisoning was investigated.

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(10% Pt ), 2--3--2- 1- .

     

Catalytic performance in Co hydrogenation over triruthenium ketenylidene cluster-derived catalyst

The ruthenium catalyst prepared from triruthenium ketenylidene cluster exhibited high catalytic activity in CO hydrogenation, compared with the catalyst from [HRu₃(CO)₁₁]^–. The high activity possibly resulted from the ketenyl group (CCO) that could be partly converted to carbide species.

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, , CO, [HRu₃(CO)₁₁]^–. , , (CCO), .

     

Br?nsted sites in H-forms of faujasites obtained from ammonium and guanidine forms

The infrared spectra of H-forms of Y zeolite made from the guanidine and ammonium forms were compared. The Brönsted acid sites have been characterized by adsorption of pyridine. Good correlation between the concentration of Brönsted acid sites and the catalytic activity of the samples has been found. It was concluded that guanidine cations limited localization of OH groups on the surface of the supercages.

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, . , . . , OH .

     

Mechanism of carbon monoxide oxidation on nickel oxide and its solid solutions

On the basis of studying the isotope exchange of oxygen and the position of the Fermi level in the system MiO–Li_xNi_1–xO, an explanation is proposed for the compensation effect in the reaction of CO oxidation on nickel oxide and its solid solutions.

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NiO–Li_xNi_1–xO CO .

     

The influence of the structure and composition of complexes of the type CuA2X2 on the courses of their thermal decomposition

The influence of different degrees of distortion of the coordination polyhedra in some Cu(II) complexes on the courses of their thermal destruction was studied. It was found that differences in the thermal stability and stoichiometry of thermal decomposition may be satisfactorily explained by the different degrees of distortion of the coordination polyhedra in the Cu(II) complexes under discussion. This fact appears to be significant with respect to the chemical reactivities of these complexes, though the influence of other factors cannot be excluded.

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Zusammenfassung Der Einfluß der verschiedenen Grade der Koordinations-Polyeder-Verzerrung in einigen Cu(II) Komplexen auf den Verlauf ihrer thermischen Zersetzung wurde untersucht. Es wurde festgestellt, daß Unterschiede in der thermischen Stabilität und der Stöchiometrie der thermischen Zersetzung durch die verschiedenen Verzerrungsgrade der Koordinations-Polyeder in den erörterten Cu(II) Komplexen befriedigend erklärt werden können. Diese Tatsache scheint hinsichtlich der chemischen Reaktivität dieser Komplexe von grosser Bedeutung zu sein, obwohl der Einfluß anderer Faktoren nicht ausgeschlossen werden kann.

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Résumé On a étudié l'influence des différents degrés de distortion des polyhèdres de coordination sur l'allure de leur décomposition thermique, dans le cas de quelques complexes du Cu(II). On a trouvé que les différences de stabilité thermique et de stoechiométrie pouvaient expliquer de manière satisfaisante les différents degrés de distortion des polyhèdres de coordination dans les complexes du Cu(II) étudiés. Ce fait semble être plutôt significatif de la réactivité chimique de ces complexes, bien que l'influence d'autres facteurs ne doive pas être exclue.

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Cu(II) . , -, Cu(II). , -, , .

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Presented at the 7th Czechoslovak National Conference on Thermal Analysis (TERMANAL); The High Tatras, 1976.     

Reaction kinetics by thermal analysis

The application of thermal analysis in the study of reaction kinetics and reaction mechanisms in combination with presently available powerful analytical tools, in the sphere of materials with particular reference to high energy materials is presented and discussed. Also an attempt has been made to correlate the kinetic data obtained by TA with the performance characteristics, for some important materials.

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Zusammenfassung Es wird die Anwendung der Thermoanalyse bei der Untersuchung der Reaktionskinetik und des Reaktionsmechanismus in Zusammenwirkung mit den gegenwärtig zur Verfügung stehenden leistungsfähigen analytischen Werkzeugen auf dem Gebiet von Materialien mit speziellem Bezug auf energiereiche Stoffe dargestellt Und besprochen. Es wurde auch versucht, die durch TA erhaltenen kinetischen Daten einiger wichtiger Stoffe mit deren Leistungskenndaten in Beziehung zu stellen.

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. , , .

     

Investigation of surface phenomena on solid catalysts by thermogravimetry

Thermogravimetry was applied to the investigation of the phenomena of adsorption, chemisorption, desorption and surface reactions on solid catalysts. The measurements were carried out with 13 NaX and NaY type zeolites and with silica gels treated with sodium hydroxide, in the presence of cumene and methanol. On the basis of the quantitative results it is possible to give an interpretation of surface phenomena and to establish the existence of various active centres on the surface of the catalysts.

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Zusammenfassung Adsorptions-, Chemisorptions- und Desorptionserscheinungen, sowie Oberflächenreaktionen an festen Katalysatoren wurden thermogravimetrisch untersucht. Die Messungen wurden an Zeoliten der Typen 13 NaX und NaY und an mit Natriumhydroxid behandelten Silikagelen in Gegenwart von Cumol und Methanol durchgeführt. Aufgrund der quantitativen Ergebnisse war es möglich, die Oberflächenerscheinungen zu deuten und das Vorhandensein von verschiedenen aktiven Zentren an der Katalysatoroberfläche nachzuweisen.

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Résumé On a appliqué la méthode thermogravimétrique à l'étude des phénomènes d'adsorption, de chemisorption et de désorption ainsi qu'aux réactions de surface sur des catalyseurs solides. Les mesures ont été effectuées sur zéolites de type 13 NaX et NaY et sur des silicagels traités par la soude en présence de cumène et de méthanol. Des résultats quantitatifs permettent de donner une interprétation des phénomènes de surface et d'établir l'existence de divers centres actifs à la surface des catalyseurs.

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, , , . , , , , . 13 NaX NaY , . .

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The authors express their gratitude to Prof. S. Malinowski for help and discussion and to Mr. W. Dziklinski for his technical help.     

Hydrogenation of carbon monoxide catalysts prepared by pyrolysis of Co2(CO)8 on various oxide supports

Catalysts prepared by pyrolysis of Co₂(CO)₈ on oxide supports have been studied in the hydrogenation of CO. It is shown that MgO and -Al₂O₃-based catalysts are less active than those supported on SiO₂, TiO₂ and ZrO₂. The application of -Al₂O₃ as a support increases the relative yield of light hydrocarbons.

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, Co₂(CO)₈ , CO. , MgO -Al₂O₃ SiO₂, TiO₂ ZrO₂. -Al₂O₃ .

     

Kinetic data on the interaction between triplet anthraquinone and 2-naphthol in oxygen

During the photooxidation of ethylbenzene in the presence of 2-naphthol a new interaction has been found between the sensitizer anthraquinone and the inhibitor. The quantum yield and the kinetics of this interaction have been investigated in the temperature interval of 28–98°C.

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-, , 28–98°C , .

     

Quantum chemical study of the physical characteristics of the hydroxy groups of zeolites, III

The CNDO/2 method was applied to calculate the electronic structure of HY zeolite using cluster models Si₃AlO₁₂H ₈ ^– and Si₃AlO₁₂H₉. It has been shown that the probability of occurrence of H on a particular type of oxygen as well as the other physical characteristics of zeolite depend on both the type of oxygen and the position of the Al atom.

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/2 , Si₃AlO₁₂H₈ Si₃AlO₁₂H₉. , , , Al.

     

Effect of carbon dioxide on the catalytic oxidation of ethylene over silver. Kinetic reaction model accounting for the modification of catalyst surface by carbonate groups

Changes in the character of catalytic oxidation of ethylene over silver upon increasing pressure of reaction mixture, reflected in increased ethylene oxide selectivity, are due to the modifying effect of suface carbonate groups. A kinetic reaction model is suggested based on the individual investigations of reaction steps.

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, , . , .

     

A study of thermal preparation OF c-Mn2P4O12

With the application of thermogravimetry under quasi-isothermal-isobaric conditions, the reaction course of the calcination of Mn(H₂PO₄ · H₂O to give dimanganese cyclotetraphosphate has been studied. Isothermal calcination was also carried out in an electric furnace at various temperatures (200 min). The reaction products were analyzed by chromatography, IR and NMR spectrocopy, and X-ray diffraction analysis. The compositions of the calcinates were determined through extraction with various inorganic and organic solvents.

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Zusammenfassung Der Verlauf der Dimangan-cyclotetraphosphat ergebenden Kalzinierung von Mn(H₂PO₄)₂ · H₂O wurde thermogravimetrisch unter quasi-isothermen-isobaren Bedingungen untersucht. Isotherme Kalzinierung wurde auch im elektrischen Ofen (200 min) bei verschiedenen Temperaturen ausgeführt. Die Reaktionsprodukte wurden chromatographisch, IR- und NMR-spektroskopisch sowie röntgendiffraktometrisch analysiert. Die Zusammensetzung der kalzinierten Produkte wurde via Extraktion mit verschiedenen anorganischen und organischen Lösungsmitteln bestimmt.

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Mn(H₂PO₄ · H₂O. . . - , - - . .