Effect of rare earth ions on the catalytic activity of Ln2MnNiO6 perovskites

Abstract A series of rare earth transition metal perovskites has been synthesized and the catalytic activity tested for 2-propanol decomposition. The effect of rare earth ions on the catalytic activity can been understood from the correlations obtained between the physico-chemical properties and the catalytic activity of the perovskites.

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, , 2-. , - .

     

Kinetic studies of hydrogen and carbon monoxide adsorption on Re2O7/Al2O3 catalysts

Kinetic studies of hydrogen and carbon monoxide adsorption on reduced Re₂O₇/Al₂O₃ catalysts have revealed that its activation energy decreases with increasing reduction degree of rhenium oxide. Adsorption of gases is suggested to take place on metallic rhenium atoms.

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- . , . , .

     

Isoparametric kinetic relations for chemical transformations in condensed substances (Analytical survey). II. Reactions involving the participation of solid substances

Various manifestations of the kinetic compensation effect are considered in reactions involving the participation of solid substances under isothermal and nonisothermal conditions, as well as manifestations of other isoparametric correlations. It is shown that isoparametric correlations can be used for the analysis of solid-phase reactions and the exclusion of artefacts in nonisothermal kinetics.

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Zusammenfassung Verschiedene Erscheinungen des kinetischen Kompensationseffektes bei unter Beteiligung von festen Substanzen unter isothermen und nichtisothermen Bedingungen verlaufenden Reaktionen werden erörtert, ebenso Erscheinungen anderer isoparametrischer Korrelationen. Es wird gezeigt, daß isoparametrische Korrelationen zur Analyse von Festphasenreaktionen und zum Ausschluß von Artifakten in der nicht-isothermen Kinetik herangezogen werden können.

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, , . .

     

Studies of supported catalysts for ethylene polymerization, prepared using organovanadium compounds

Catalysts containing trimethylsilyl complexes of V(IV) and (III) supported on SiO₂ and Al₂O₃, have been synthesized and examined for ethylene polymerization. The state of vanadium in solution and on the support and catalysts interaction with C₂H₄, CO, H₂ and pyridine have been studied using ESR and IR spectroscopy.

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, (IV) (III), SiO₂ Al₂O₃. , C₂H₄, CO, H₂ .

     

The thermal analysis of “argentic oxynitrate” and silver oxides

The precise stoichiometry of argentic oxynitrate has been elucidated by analytical and thermal analytical techniques. A decomposition path of the oxynitrate has been proposed and values of the enthalpy changes obtained. TG has been used as the criterion of purity of silver(II) oxide and new values for the heat of formation of silver(I) and silver(II) oxide are reported.

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Zusammenfassung Die genaue Stöchiometrie des Silberoxynitrats wurde durch analytische und thermoanalytische Prüfung geklärt. Der Zersetzungsvorgang des Oxynitrats wurde verfolgt und die Enthalpieänderungen beobachtet. Die Reinheit von Silber(II)oxyd läßt sich thermogravimetrisch kontrollieren. Es wurden neue Werte für die Bildungswärmen des Silber(II)oxyds und Silber(I)oxyds gefunden.

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Résumé Etude de la stoechiométrie précise de l'oxynitrate argentique par les techniques analytiques et thermoanalytiques. On propose un schéma de décomposition de l'oxynitrate et l'on évalue les variations d'enthalpie. Emploi de la TG comme critère de pureté de l'oxyde d'argent(II). Communication de nouvelles valeurs pour les chaleurs de formation des oxydes d'argent (I) et d'argent (II).

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. . (II) . (I) (II).

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The authors wish to thank Mr. J. McEwan and Mrs. I. M. Walker for valuable practical assistance and the United Kingdom Atomic Energy Authority for financial support.     

Acidity dependence of aniline alkylation activity over modified alumina+

-Al₂O₃ is modified by lithium additions and by calcination. Aniline alkylation activity over modified alumina is correlated with the Al–OH group population responsible for the acidity.

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-Al₂O₃ . Al–OH, .

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IICT Communication No.: 2824     

The influence of CSH phase nuclei on Ca3SiO4Cl2 hydration

The influence of CSH phase nuclei on calcium chlorosilicate hydration has been studied by means of calorimetry, QXRD, DTA and TG methods.

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Zusammenfassung Mittels kalorimetrischen, QXRD-, DTA- und TG-Verfahren wurde der Einfluß von CSH Phasenkörpern auf die Hydratierung von Kalziumchlorosilikat untersucht.

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, , .

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C=CaO, S=SiO₂, H=H₂O     

Dehydroxylation and catalytic activity of dealuminated Y zeolites

Dehydroxylation and catalytic conversion of m-xylene over dealuminated zeolites were studied.

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- .

     

Kinetic luminescence measurements on the interaction of oxygen with oxide surfaces

The dependence of luminescence intensity on the reaction conditions on oxide surfaces permits to determine the kinetic mechanism and gas-surface interaction constants. The suggested method was realized as a computer algorithm.

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-. .

     

Hydrogenation and hydrogenolysis of methylcyclohexane-1,4-dione on Pt and Pd catalysts

Relative hydrogenation reactivity of the two carbonyl groups of methylcyclohexane-1,4-dione can be estimated beside that of two related compounds, 2- and 3-methyl-cyclohexanones. The reaction is accompanied with hydrogenolysis on Pt and Pd. The less hindered 4-carbonyl group is selectively hydrogenolyzed.

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-1,4- , 2- 3-. Pt Pd. 4- .

     

Catalysts for metathesis of olefins, prepared by anchoring of MoO2(acac)2 to Al2O3

New highly active catalysts for metathesis of olefins were obtained through the interaction of bis(acetylacetonato)dioxymolybdenum(VI) with surface OH groups of -Al₂O₃ and subsequent reduction in H₂ or CO.

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()(VI) OH -Al₂O₃ H₂ CO .

     

Transalkylation of phenols over heteropoly acids

Transalkylation of 2,6-di-tert-butyl-4-R-phenols over solid heteropoly acids (H₃PW₁₂O₄₀, H₄SiW₁₂O₄₀, H₃PW₁₂O₄₀/SiO₂, H₄SiW₁₂O₄₀/SiO₂) in the presence of toluene or o-xylene as acceptors of a tert-butyl group at 100–140 °C produces 4-R-phenols with 92–98% yield (R = H, alkyl, aryl, etc.). HPAs are effective catalysts for the transalkylation of p-cresol and 2, 6-ditert-butyl-4-methylphenol.

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2,6----4-R- (H₃PW₁₂O₄₀, H₄SiW₁₂O₄₀, H₃PW₁₂O₄₀/SiO₂, H₄SiW₁₂O₄₀/SiO₂) 0- - 100–140°C 4-R- 92–98% (R = H, , ..). - 2,6----4-.

     

Kinetics of CO hydrogenation on group VIII metals

Kinetics of CO hydrogenation on supported Group VIII metals has been studied. Kinetic equations for CO methanation and Fischer-Tropsch synthesis suggested previously are consistent with the experimental data obtained.

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CO VIII . CO -, , .

     

Kinetics of catalyst regeneration by coke combustion. II. Influence of temperature rise in the catalyst particles

A grain-pellet model has been used to study the effect of high reaction rates upon the temperature profiles developed during regeneration of coked catalyst particles. The possibility of falsification of kinetic data is discussed in view of the results obtained.

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- , . .

     

Kinetics and mechanism of the oxidation of p-aminobenzoic acid by periodate ion in aqueous medium

Kinetic results of the oxidation of p-aminobenzoic acid by periodate ion in aqueous medium are discussed. A suitable mechanism based on kinetic evidence and product analysis is proposed.

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- . , .

     

Mass-spectrometric analysis of polymers based on furyl alcohol-polyamic acid compositions

Polymer compositions based on furyl alcohol and polyamic acid were investigated by using mass-spectrometric thermal analysis. It was established that polyamic acid catalyses both the polycondensation of furyl alcohol and the formation of a three-dimensional network of furan polymer.

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Zusammenfassung Mittels massenspektroskopischer Thermoanalyse wurden auf Furylalkohol und Polyamidsäure basierende Polymergemische untersucht. Es wurde festgestellt, daß Polyamidsäure sowohl die Polykondensation von Furylalkohol als auch die Bildung eines dreidimensionalen Furanraumnetzes katalysiert.

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- . , , .

     

Catalytic properties of nickel phosphates. Isomerization of butenes

The effect of calcination temperature on the catalytic properties of nickel phosphate has been studied using the isomerization of butene-1 as a test reaction. A simple relationship was found between the catalyst activity in isomerization and the hydroxy content of the catalyst surface. Interrelations between the activity of the catalyst and its structure are discussed.

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, -1 . . .

     

Low-temperature oxidation of CO to CO2 in solutions of halide complexes of Pt and heteropolyacid (HPA)

Kinetics of oxidation of Co to CO₂ in solutions of halide complexes of Pt(IV) and HPA at room temperature has been studied. A reaction mechanism is suggested. The catalyst Pt+HPA is stable at T=0–50°C and 0.9<pH<2.5.

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CO CO₂ Pt(IV) . . Pt+ 0–50°C 0,9<pH<2,5.

     

Comparison of the sulfurization of CoMoK/Al2O3 catalyst with H2S and CS2

Only H₂S consumption and H₂O formation was found in the sulfurization of CoMoK/Al₂O₃ water gas shift catalyst with H₂S/H₂, but CO₂ was formed first, then CH₄, H₂O and H₂S appeared in the later part of TPS with CS₂/H₂. Carbon deposition on the catalyst during the sulfurization with CS₂/H₂ caused a lower activity than the catalyst sulfurized with H₂S but could be removed in the run of WGS reaction.

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, CoMoK/Al₂O₃, H₂S/H₂ H₂S H₂O, CS₂/H₂ CO₂ CH₄, H₂O H₂S. CS₂/H₂ H₂S, , .

     

Performance of a cobalt oxide catalyst in the oxidation of NH3 to NO

The cause for a fall in the conversion of NH₃ to NO within 73 hours from 97% to 78% with a cobalt oxide catalyst was investigated. Results show that sintering, change in valence and cation distribution in Co₃O₄ contribute to the decrease in activity. Incorporation of ThO₂ and K₂O improves the performance of the catalyst.

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NH₃ NO 73 97% 78%. , , Co₃O₄. ThO₂ K₂O NH₃ NO.