Influence of ammonia on propane oxidation over a gallium-antimony oxide catalyst

The influence of ammonia on propane oxidation over a Ga–Sb oxide catalyst has been studied. Acrylonitrile is formed upon the interaction of acrolein with partially dehydrogenated ammonia. Ammonia increases the rates of overall and selective oxidation of propane. This is assumed to be due to the formation of electron-donor sites promoting proton separation from the propane molecule.

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. , . . , , .

     

Thermal studies on some group VIII complexes with biologically active ligands

The mode of decomposition of complexes involving biologically important ligands such as thiouracil and xanthine coordinated to some group VIII metals has been studies by thermogravimetry. The results show that the complex tris-(dithiouracil) trichlororhodium(III) is monomeric and not polymeric as suggested previously. The decomposition behavior of the complex indicates that after the initial loss of a ligand molecule to form a four-coordinate complex, further ligand removal takes place in one sharp step. In the case of the complexes bis-(3-methylxanthine) diammineplatinum(II) and bis-(9-methylxanthine) diamminepalladium(II), ammonia comes off first, followed by rapid loss of the remaining xanthine ligands. Moreover, the activation energy determined for the main decomposition step suggests that the breakdown of the xanthine ligand involves the initial cleavage of the pyrimidine moiety, followed closely by loss of the remaining imidazole portion.

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Zusammenfassung Die Art der Zersetzung von Komplexen einiger Metalle der VIII. Gruppe mit biologisch wichtigen Liganden, wie Thiouracil and Xanthin, wurde thermogravimetrisch untersucht. Die Ergebnisse zeigen, daß der Komplex Tris-(dithiouracil) trichlororhodium(III) monomer und nicht — wie früher vermutet — polymer ist. Das Zersetzungsverhalten des Komplexes zeigt, daß nach dem zu einem tetrakoordinierten Komplex führenden Verlust eines Ligandmoleküls die Abgabe eines weiteren Liganden in einem scharfen Schritt erfolgt. Im Falle der Komplexe Bis-(3-methylxanthin) diamminplatin(II) und Bis-(9-methylxanthin) diamminpalladium(II) erfolgt zunächst eine Abspaltung von Ammoniak, der ein schneller Verlust der verbleibenden Xanthinliganden folgt. Die für die Hauptzersetzungsreaktion bestimmte Aktivierungsenergie läßt vermuten, daß der Abbau der Xanthinliganden über eine Spaltung des Pyrimidinteils verläuft, der schnell die Abgabe des verbleibenden Imidazolteils folgt.

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, , VIII . , -() (III) , , . - , . - (3-) (II) -(9 -) - (II) -(II) , . , , , , .

     

Kinetics of heterogeneous catalytic hydroformylation of propylene on rhodium-cobalt catalysts. Reaction mechanism

Steady-state kinetics of combined heterogeneous catalytic hydrogenation and hydroformylation of propylene on Rh–Co-containing catalysts has been studied at atmospheric pressure and T=140–170 °C. A reaction mechanism is suggested. The kinetic model adequately describes all observations.

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- Rh–Co- 140–170 °C. . , .

     

Dehydration kinetics by non-isothermal techniques

The kinetics of thermal degradation of some cementitious calcium aluminates, sulfoaluminates, sulfoferrites and carboaluminates were studied. Activation energies, obtained by Morris and Rogers and Kissinger techniques, were found to be in good agreement with each other.

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Zusammenfassung Die thermische Zersetzungskinetik einiger im Zement befindlicher Kalziumaluminate, Sulfoaluminate, Sulfoferrite und Karboaluminate wurde untersucht. Die nach den Methoden von Morris und Rogers, sowie Kissinger erhaltenen Aktivierungsenergien stimmten gut überein.

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Résumé On a étudié la cinétique de la décomposition thermique de plusieurs constituants du ciment tels les aluminates, sulfoaluminates, sulfoferrites et carboaluminates de calcium. Les énergies d'activation obtenues en appliquant la méthode de Morris et Rogers ainsi que celle de Kissinger sont concordantes.

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-, -, . , , , , .

     

X-ray analysis of Pt?Sn catalysts supported on zinc-aluminium spinel

An x-ray diffraction analysis of Pt–Sn catalysts supported on zinc-aluminium spinel has shown that, after testing in paraffin dehydrogenation, they contain a tin-platinum solid solution with a face-centered cubic cell.

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, - , , .

     

A device for pulse investigation of heterogeneous catalytic reactions

In the present work a simple device is described for the pulse investigation of heterogeneous catalytic reactions and catalysts. Owing to the possibility for separate adjustment of the gas flow rate in the catalytic reactor and in the chromatographic column, it can be used for kinetic measurements too.

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- . , .

     

V2O5/TiO2 oxidation catalysts, IV. Adsorption of acrolein on sodium-containing systems

Adsorption of acrolein on vanadia/titania catalysts fits a polymerization kinetics if Na–V compounds are not present or the vanadium content is lower than that corresponding to formation of a monolayer of vanadia on the titania support.

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, Na–V .

     

Nitrate and sulfite catalyzed reaction of monooxalatotetraaquachromium(III) and ethylenediaminetetraacetate

The kinetics of the reaction between monooxalatotetraaquachromium(III) and ethylenediamenetetraacetate have been studied in acidic media. The reaction is accelarated by nitrite and sulfite ions. The mechanism for the catalyzed reaction is discussed in terms of the formation of Cr(ONO)(ox)(H₂O)₃ and Cr(OSO₂H)(ox)(H₂O)₃. The catalytic effect of sulfite is greater than that of nitrite. Spectral evidence is presented for the formation of nitrito and sulfito species.

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() (III) . , . Cr(ONO)(ox)(H₂O)₃ Cr(OSO₂H)(ox)(H₂O)₃. . .

     

Properties of highly dispersed supported catalysts in hydrogenation reactions

Pt/sol and Pt/support catalysts with 6–15 Å Pt particles have been established to be low active in the hydrogenation of propargyl alcohol, butyn-l-ol-3 and dimethylethynylcarbinol. The specific catalytic activity significantly rises with increasing d_Pt above 15 Å and after the thermal treatment of highly dispersed catalysts in a hydrogen flow.

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, -30 -- 6–15 Å , -1, -3 . d_Pt>15 Å .

     

Mise au point d'un appareil d'analyse thermique dans l'intervalle 300<t<600 k et son utilisation pour la mesure de la purete de substances,de la temperature de leur point triple et de leur enthalpie de fusion

In this paper is described an apparatus for differential thermal analysis which was conceived realized and tested in authors' laboratory.The experiments carried on gave results which show that this apparatus can be used to determine with a good accuracy and reproducibility the purity of a compound and the temperature of its triple point and its enthalpy of fusion in the range 300–600 K.It is clear that this apparatus can also be used to study the stability of a substance in the same range of temperature.

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Zusammenfassung Es wird eine zur Differentialthermoanalyse geeignete Apparatur beschrieben, die in den Laboratorien der Autoren entwickelt, gebaut und getestet wurde. Die Ergebnisse der durchgeführten Experimente zeigen, daß dieses Gerät im Bereich von 300 bis 600 K eine genaue und reproduzierbare Bestimmung von Reinheit, Tripelpunkt und Bildungsenthalpie einer Verbindung ermöglicht. Die Apparatur kann natürlich im selben Temperaturbereich auch zur Stabilitätsuntersuchung eines Stoffes dienen.

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, , . , , 300–600 . .

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A qui les demandes de tirés à part devront être adressées.     

Solvent effects in the photolysis of 1,2,3,4-tetrahydro-1-naphthylhydroperoxide. Photocatalytic effect of Co(III) 2,4-pentanedionate

The effect of various solvents on the photoinitiated decomposition of 1,2,3,4-tetrahydro-1-naphthylhydroperoxide (THP) with and without added Co(III) 2,4-pentanedionate has been studied. The conversion of THP, formation of major products and change in the oxidation state of the metal ion have been investigated in different solvents.

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1, 2, 3, 4--1- () Co(III) 2,4-. , .

     

Structure of the species formed from molybdenum naphthenate in the reaction with 1-phenylethyl hydroperoxide

IR and elemental analysis data indicate that the probable structure of the title compound is MoOL₂ORH or MoOL₂OORH which is formed directly from the radical within the coordination sphere of the catalyst (L=ligand).

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- , , , MoOL₂ORH MoOL₂OORH. (L=).

     

Oxidative dehydrogenation (OXD) of n-butane I. Activity of natural quartz II. Kinetic and catalytic activity of nickel oxides

The oxidative dehydrogenation of n-butane on nickel oxide catalysts and on natural quartz, used as catalysts diluent, were studied. It is assumed that oxygen ions from the oxide lattice participate in the initial step of the reaction.

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- , . , .

     

A thermal synthesis of a new tin(IV) dithiocarbamate

A new tin dithiocarbamate containing sulphur bridges, di--sulphidobis [bis(N,N-diethyldithiocarbamato)tin(IV)], has been isolated from the thermal decomposition of tetrakis(N,N-diethyldithiocarbamato)tin(IV). A dimeric structure is proposed on the basis of results from mass spectrometry, infrared spectroscopy, thermal analysis and vapour pressure osmometry.

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Zusammenfassung Ein neues, Schwefelbrücken enthaltendes Zinn-Dithiocarbamat, Di--sulfidobis[bis(N,N-diäthyldithiocarbamato)Zinn(IV)], wurde bei der Zersetzung von Tetrakis(N,N-diäthyl-dithiocarbamato)Zinn(IV) isoliert. Aufgrund der Ergebnisse der Massenspektrometrie, der Infrarotspektroskopie, der Thermoanalyse und der Dampfdruck-Osmometrie wird eine Dimerstruktur vorgeschlagen.

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Résumé Un nouveau dithiocarbamate d'étain contenant des ponts de soufre, le di--sulfidobis[bis(N,N-diéthyl-dithiocarbamato)é tain(IV)], a été isolé lors de la décomposition thermique du tétrakis(N,N-diethyl-dithiocarbamato) étain(IV). Une structure dimère est proposéeà partir des résultats obtenus par spectrométrie de masse, spectroscopie infrarouge, analyse thermique et osmométrie sous pression de vapeur.

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—-- [/N,N- (/IV)], [/N,N- (/IV)], , (N,N- ) (IV). - , , .

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The authors gratefully acknowledge the assistance given by Dr. A. G. Wedd with the vacuum sublimation technique. One of us, G. K. B., is grateful for a research scholarship provided by La Trobe University.     

Support and mixing effect of an Fe2O3 catalyst for oxidative dehydrogenation of 1-butene

The support and mixing effects of Fe₂O₃ for the activity of 1-butene oxidative dehydrogenation were examined. Alumina and titania which were able to catalyze the isomerization of butene via an allyl intermediate, stimulated remarkably the formation of butadiene from butene when they were used as support or mixing component of Fe₂O₃ catalyst. Otherwise Fe₂O₃ supported on SO ₄ ^2– ion containing Al₂O₃ or TiO₂–Al₂O₃, which catalyze the isomerization via a cationic intermediate, is almost inactive for the formation of butadiene.

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Fe₂O₃ 1-. , , , Fe₂O₃. , Fe₂O₃, Al₂O₃, SO ₄ ^–2 , TiO₂–Al₂O₃, , .

     

Study of thermal behaviour up to 1550° of materials containing calcium sulphate

Thermal analysis up to 1550 °C on natural and synthetic materials containing CaSO₄ revealed the temperature ranges of dehydration, impurity content decomposition and CaSO₄ decomposition. CaSO₄ decomposition starts above 1200 °C and proceeds in several steps, depending on the CaO content. CaSO₄ forms several eutectic compositions with CaO (at 1340, 1390, 1410 and 1450 °C), each decomposition step being preceded by the formation and fusion of a eutectic composition, the decomposition taking place in the melt.

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Zusammenfassung Die thermische Analyse bis 1550 °C von CaSO₄ enthaltenden natürlichen und synthetischen Materialien hat gezeigt, daß Temperaturbereiche zu unterscheiden sind, in denen die Dehydratisierung und die Zersetzung von Verunreinigungen und CaSO₄ verlaufen. Die Zersetzung von CaSO₄ setzt oberhalb 1200 °C ein und verläuft, abhängig vom CaO-Gehalt der Probe, in mehreren Schritten. Es wurde festgestellt, daß Calciumsulfat mit CaO mehrere eutektische Gemische (bei 1340, 1390, 1410 und 1450 °C) bildet. Jedem Zersetzungsschritt geht die Bildung und das Schmelzen eines eutektischen Gemischs voraus. Die Zersetzung selbst geht in der Schmelze vor sich.

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1550 °, , , , , . 1200 ° , . , 1340, 1390, 1410 1450° . , .

     

Thermal decomposition of tetraamineplatinum(II) chloride by simultaneous TG/DTG/DTA/MS and direct insertion probe mass spectrometry

Simultaneous thermogravimetry (TG), derivative thermogravimetry (DTG), differential thermal analysis (DTA), and evolved gas analysis (EGA) by mass spectrometry (MS) have been used to determine the decomposition path for tetraamineplatinum(II) chloride and cis- and trans-diamineplatinum(II) chloride. Unequivocal identification of the evolved gases was done by direct insertion probe mass spectrometry.The thermal decomposition of (NH₃)₄PtCl₂ occurred in two steps. The first was endothermic loss of two moles of ammonia producing a mixture of cis- and trans-diaamineplatinum(II) chloride. The second step was decomposition of the diamine complex to metallic Pt and N₂, HCl, and NH₄Cl. Reduction of Pt(II) to metallic Pt was coupled with oxidation of ammonia to molecular nitrogen and protons.

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Zusammenfassung Simultane Thermogravimetrie (TG), derivative Thermogravimetrie (DTG), Differentialthermoanalyse (DTA) und Analyse der entwickelten Gase (EGA) durch Massenspektrometrie (MS) wurden zur Bestimmung des Reaktionsverlaufs bei Zersetzung von Tetraminplatin(II)-chlorid sowie cis- und trans-Diaminplatin(II)-chlorid herangezogen. Die eindeutige Identifizierung der entwickelten Gase erfolgte durch Massenspektrometrie mit direkter Probeneinführung. Die thermische Zersetzung von (NH₃)₄PtCl₂ erfolgt in zwei Schritten. Der erste ist die endotherme Abspaltung von zwei Mol Ammoniak unter Bildung eines Gemisches von cis- und trans-Diamin-platin(II)-chlorid. Der zweite Schritt ist die Zersetzung des Diaminkomplexes zu metallischem Pt, H₂, HCl und NH₄Cl. Die Reduktion von Pt(II) zu metallischem Pt ist mit der Oxydation von Ammoniak zu molekularem Stickstoff und Protonen gekoppelt.

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-, -, -, - - (II) - (II) . (II). -. (NH₃)₄PtCl₂ . - -(NHN₃)₂PtCl₂. , , . .

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The technical assistance of G. J. Dechert is gratefully acknowledged.     

Formation of the active component of a vanadium complex catalyst for the oxidation of anthracene to anthraquinone

The phase composition in various stages of preparation of the active material coating the catalyst for the partial oxidation of anthracene to anthraquinone was studied. The presence of an active phase was evidenced in the final active material as well in a precursor.

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, . , .

     

Effect of hydrogen pressure on the selectivity of 2-butene-1-al hydrogenation

The effect of hydrogen pressure on the selectivity of hydrogenation of 2-butene-1-al at the carbonyl group in the presence of Ru and Ru–ZnO catalysts indicates that the selectivity on the modified ruthenium catalyst in the pressure range of 0.51–8.08 MPa is a maximum at .

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-2--І Ru Ru–ZnO-. , 0,51–8,08 , .