Decomposition of isopropanol on V2O5 of different grain morphology and its relation to o-xylene oxidation catalysts

Decompositon of isopropanol has been studied on V₂O₅ samples of different morphology. It has been shown that the selectivity to acetone increases with the increase in the fraction of (010) plane of V₂O₅ on the sample surface, whereas the selectivity to propene decreases. The results are compared with previous data of o-xylene oxidation on the same samples and discussed in terms of the model of V₂O₅ surface [7].

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V₂O₅ . , (010) V₂O₅ , . - V₂O₅.

     

A model of reduction mechanism of rhenium in Re/Al2O3 catalysts

In Re/Al₂O₃ there exist a monolayer type of Re and a second one which is inserted in the alumina lattice. The latter is reduced by a two-step mechanism including Re(IV) species.

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Re/Al₂O₃ , . , Re(IV).

     

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) . , , .

     

V2O5/TiO2 oxidation catalysts, III. Oxidation of CO on pure and sodium-doped systems

The activity of vanadia/titania catalysts in CO oxidation has been tested and found to be of the same order as that observed for unsupported vanadia; the simultaneous presence of vanadium-sodium compounds cancels the activity, probably because of the elimination of labile V=0 species at surface defects.

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V₂O₅/TiO₂ CO, V₂O₅; - , , V=0 .

     

Hydrogen adsorption on chromia-supported iridium catalyst

Effect of thermal pretreatment of chromia-supported iridium catalyst on hydrogen adsorption was studied. It was found that the hydrogen uptake by Ir/Cr₂O₃ was highly dependent on the reduction temperature. The catalyst proved to be resistant to sintering in oxygen atmosphere at temperatures up to 700 °C and it showed symptoms of redispersion even at 650 °C.

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. Ir/Cr₂O₃ . 700°C, , 650°C .

     

Reduction behavior of Cu?SiO2 catalyst prepared by ion exchange for selective dehydrogenation to produce methyl formate from methanol

Reducibility of Cu–SiO₂ catalyst prepared by ion exchange method, being effective for selective dehydrogenation to produce methyl formate from methanol at lower temperatures, has been studied by a TPR technique. The results suggest that easier reduction leads to an increase of dispersity of Cu particles.

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, - , , . , , Cu.

     

Kinetic equation of heterogeneous catalytic isotope exchange

A kinetic equation is derived for the bimolecular isotope exchange reaction between AX _n ^* and BX _m ^o , all atoms of element X in each molecule being equivalent. The equation can be generalized for homogeneous and heterogeneous catalytic isotope exchange.

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, AX _n ^* BX _m ^o , X . , - .

     

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, .

     

Kinetics of isotope exchange of dioxygen with a powdered high-temperature superconducting material Ba2YCu3O7?x

It has been found that the rate of isotope exchange in Ba₂YCu₃O_7–x–O₂ system is high. Its kinetics is exponential, first order with respect to dioxygen and the exchange is of the mixed first/third type.

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Ba₂YCu₃O_7–x–O₂ . -, -, - .

     

Ba(OH)2 as catalyst in organic reactions. VIII. Nature of the adsorbed species in Claisen-Schmidt reaction

The nature of the adsorbed species in the synthesis ofo-hydroxychalcones by Claisen-Schmidt reaction catalyzed by C-200 is analyzed by IR. The presence of the adsorbed carbanion fromo-hydroxyacetophenone in the surface of the catalyst is proved. The aldehyde molecule is adsorbed too. The mechanism of the surface reaction is discussed.

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- -, C-200, -. - . . .

     

A thermoanalytical study on some compounds of Zr(IV) with azopyrazolonic derivatives

Thermoanalytical data on six reagents and on their compounds with Zr(IV) are reported. Except for H acid, all reagents were azopyrazolonic derivatives obtained by synthesis. The purpose of this study was to obtain data on the thermal stabilities of the reagents and their zirconium compounds, and to establish the reagent: zirconium: water combination ratio.

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Zusammenfassung Thermoanalytische Daten von 6 Reagenzien und deren Verbindungen mit Zr(IV) werden mitgeteilt. Außer H-Säure waren alle Reagenzien durch Synthese erhaltene Azopyrazolon-Derivate. Zweck der Untersuchung war, Daten über die thermische Stabilität dieser Reagenzien und ihrer Zirkonverbindungen zu erhalten und das Verhältnis Reagens: Zirkon: Wasser festzustellen.

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. , , - . , : : .

     

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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. . , .

     

Parent and mixed ligand complexes in the copper(II)-ethylene glycol-sulphate system

Eleven copper(II)-ethylene glycol-sulphate complexes of different compositions were prepared, one of them-CuGl₂(H₂O)₂SO₄-in single-crystal form. A thermoanalytical study of these complexes revealed three types of thermal decomposition pattern. The X-ray structure of the single-crystal demonstrated the presence of ethylene glycol bridges resulting in endless chains in the crystal.

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Zusammenfassung Elf Kupfer(II)-äthylenglykol-sulfat-Komplexe unterschiedlicher Zusammensetzung wurden dargestellt, einer davon — CuGl₂(H₂O)₂SO₄ — in Form von Einkristallen. Die thermoanalytische Untersuchung dieser Komplexe ergab drei Typen der thermischen Zersetzung. Die röntgendiffraktometrische Bestimmung der Struktur des in Form von Einkristallen erhaltenen Komplexes zeigte, daß den Kristall endlose Ketten von Äthylenglykolbrücken durchziehen.

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() — , — CuGl₂(H₂O)₂SO₄ — . . , , .

     

Thermal decomposition of the solvent-extracted chloro complexes of vanadium(IV) with trioctylamine and trioctylmethylammonium chloride

The complexes (R₃NHVO(OH)Cl₂)₂ and (R₃RNVO(OH)Cl₂)₂ prepared by drying in vacuo the organic solutions from the extraction into benzene of aqueous vanadyl chloride solution with trioctylamine (TOA, R₃N) and trioctylmethylammonium chloride (TOMAC, R₃RNCl), were studied by thermogravimetry and differential thermal analysis under an atmosphere of nitrogen, and the products of their thermal decomposition, such as volatile matter and residues, by gas chromatography. X-ray diffraction and infrared spectroscopy. It was found that the complexes with TOA and TOMAC thermally decompose to V₂O₃ at 200–300° by cracking of the compounds R₃NHVO(OH)Cl₂ and R₃RNVO(OH)Cl₂ formed via dissociation of the complexes at about 150°.

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Zusammenfassung Die Komplexe (R₃NHVO(OH)Cl₂)₂ und (R₃RNVO(OH)Cl₂)₂ wurden hergestellt, indem benzolische und wässrige Vanadylchlorid-Lösungen mit Trioctylamin (TOA, R₃N) und Trioctylmethylammoniumchlorid (TOMAC, R₃RNCl) extrahiert und die erhaltenen Lösungen im Vakuum eingedampft wurden. Die Komplexen wurden in Stickstoffatmosphäre mittels TG und DTA untersucht und die thermischen Zersetzungsprodukte, und zwar sowohl die flüchtigen Verbindungen als auch die Rückstände, gaschromatographisch bzw. röntgendiffraktometrisch und IR-spektroskopisch bestimmt. Es wurde festgestellt, daß die Komplexe mit TOA und TOMAC bei 150° in die Verbindungen R₃NHVO(OH)Cl₂ und R₃RNVO(OH)Cl₂ dissoziieren, die bei 200–300° thermisch zu V₂O₃ zersetzt werden.

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(R₃NHVO(OH)Cl₂)₂ (R₃RNVO(OH)Cl₂)₂ (R₃,) ( , R₃RNCl). , , . , 200–300° V₂₃ R₃NV()l₂ R₃RNVO(OH)Cl₂, 150°.

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We wish to thank the Koei Chemical Co. Ltd. for samples of TOA and TOMAC.     

Study of propylene adsorption and conversion on a gallium-molybdenum catalyst by IR spectroscopy and thermodesorption techniques

A study of propylene adsorption on gallium molybdate by IR spectroscopy and thermodesorption techniques has shown that propylene is adsorbed in reversible (-allyl) and irreversible (carboxyl, carbonate and formate) forms. The analysis of the spectra observed is supported by deuterated propylene adsorption. The conversion of the surface -allyl complexes into an Me–O–CH₂–CH=CH₂ type compound is followed.

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- , - : , . , . - Me–O–CH₂–CH=CH₂.

     

Influence of a catalytic reaction on the surface composition and roughness factor of palladium-ruthenium alloys

Using X-ray photoelectron spectroscopy (XPS) and differential flow methods, the surface composition and surface area of Pd–Ru alloys have been examined before and after their use as catalysts. The increase in the catalytic activity of the alloys leads to the enrichment of their surface in ruthenium. It is concluded that the catalytic activity of these alloys is governed by the composition, structure and (to a lesser degree) the roughness of the surface.

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Pd–Ru . . , , .

     

Acid-base properties of supported vanadium oxide catalyst

Reduction of V₂O₅/Al₂O₃ and V₂O₅/silica-alumina produced Lewis acid sites which could strongly adsorb CO (heat of adsorption: 90 kJ/mol). Such strong acid sites were not formed in the cases of V₂O₅/SiO₂ and V₂O₅/MgO. V₂O₅ loaded on Al₂O₃ interacted with the basic sites of alumina but not with the acidic sites, while the V₂O₅ on silica-alumina interacted with the acidic sites of the silica-alumina and decreased its acidity.

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V₂O₅/Al₂O₃ V₂O₅/SiO₂–Al₂O₃ , CO ( 90 /). V₂O₅/SiO₂ V₂O₅/MgO . V₂O₅, Al₂O₃, , , V₂O₅ SiO₂–Al₂O₃ - .

     

Studies of calciomagnetite phase by means of thermal analysis

Iron oxides doped with calcium occur in such natural metallurgical materials as sinters and lumps for the blast furnace process. In this work the Ca-doped magnetite phase Fe_3–y Ca _y O₄ with 0<y0.55 was produced and studied as a pattern phase for investigation of the magnetite phase in sinters.The synthesis process was studied by means of simultaneous thermal analysis, while the synthesized products were studied by diffraction analysis, scanning and optical microscopy, and spectral analysis in microareas.The solubility limits for Ca in magnetite were estimated, and an explanation of the shapes of the thermal curves was given.

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Zusammenfassung Mit Kalzium versetzte Eisenoxide kommen in natürlichen Metallurgiematerialien wie z. B. Sintererzen und Erzbrocken für die Hochofenverhüttung vor. In vorliegender Arbeit wird die kalziumversetzte Magnetitphase Fe_3–y Ca _y O₄ mit 0<y0.55 hergestellt und als Modellphase zur Untersuchung von Magnetitsintererzen studiert. Der Syntheseprozeß wurde mittels gleichzeitiger Thermoanalysen, die synthetisierten Produkte durch Diffraktionsanalysen, optischer und Scanningmikroskopie sowie Spektralanalyse im Mikrobereich untersucht. Die Löslichkeitsgrenzen von Kalzium in Magnetit wurden abgeschätzt und eine Erklärung für den Verlauf der thermischen Kurven gegeben.

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, , , . Fe_3–y Ca _y O₄ 0<y0,55 . , - , , . .

     

Structure of vanadium phosphate anion in solutions from17O,51V and31P NMR data

¹⁷O,⁵¹V and³¹P NMR studies indicate that the anion structure of sodium vanadophosphate in an aqueous solution is close to that in crystals of the (CN₃H₆)₈HPV₁₄O₄₂ 7H₂O salt.

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¹⁷O,⁵¹V,³¹P , (CN₃H₆)₈HPV₁₄O₄₂ 7H₂O.

     

Effect of catalyst surface modification on pentachlorobutene-1 oxidation to dichloromaleic anhydride

Modification of V–P–O catalyst surface by reaction products changes the reaction course and increases its catalytic activity in pentachlorobutene-1 oxidation to dichloromaleic anhydride.

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V–P–O . -1 .