Comparison of activities of cracking catalysts containing ZSM-5 and Y-zeolite

Studies on the catalytic cracking of diesel oil fraction with the boiling range of 493–603 K on H-ZSM-5 and RE, H-Y zeolites has been carried out. The results show that in the presence of H-ZSM-5 zeolite no significant increase in the yield of gasoline is observed. Higher percentage of unsaturated hydrocarbons in the gasoline and gases indicates that the hydrogen transfer activity of H-ZSM-5 containing catalyst is lower than that of RE, H-Y zeolites.

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H-ZSM-5 RE, H-Y , 493–603 . H-ZSM-5 . , , H-ZSM-5 , RE, H-Y .

     

Estimation of nonlinear relaxation of catalytic reactions

Nonlinear relaxation time has been considered as a differential characteristic determined by the reciprocal value of the relative decrease in the deviation rate of the current concentration vector of intermediates from that of their steady-state concentrations. This characteristic is used for the analysis of some model reactions.

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, , .

     

Oxidation of propene over various doped tungsten oxides

The oxidation of propene was studied on several tungsten oxides which contained small amounts of Ti, Ta, Nb and Sn. Only the Sn-containing specimen was found to be selective in the conversion of propene to acrolein. The catalytic results are correlated with crystal structures determined by electron microscopy.

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, Ti, Ta, Nb Sn. , , Sn, . , .

     

Dehydrocyclization of 1-heptene-1-14C over chromia on non-acidic alumina

The dehydrocyclization of 1-heptene-1-¹⁴C has been investigated over a chromia on nonacidic alumina catalyst with the aim of determining the¹⁴C distribution in the ring of the toluene product. As high as 80% of the¹⁴C was consistently found in the methyl position as predicted for direct six-carbon ring formation.

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1--1-C¹⁴ , , C¹⁴ . 80%- C¹⁴ , .

     

Calculation of the rate of SO2 oxidation to SO3

Approximate equation to calculate the effectiveness factor of catalyst for SO₂ oxidation to SO₃ has been derived. Calculated data agree well with those predicted by a quasi-homogeneous model.

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. .

     

Effect of substituent on the mechanism of oxidation of anilines by acidic iodate. A kinetic study

The nature of the substituent is found to exhibit a profound influence on the mechanism of oxidation of anilides by iodate. The process appears to be smooth with electron-releasing groups, while it involves consecutive reactions with electron-withdrawing groups. Azobenzenes and quinones are obtained as the major products with electron-releasing and withdrawing groups, respectively.

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. - , - . -, .

     

Collisional energy transfer in the decomposition of 2-methyloxetane and 3-methyloxetane, I. Gas/gas collisions

The pressure dependence of the unimolecular rate constants for the thermal decomposition of 2-methyloxetane and 3-methyloxetane has been studied. The average energy transferred downward in gas-gas collision was determined by the application of RRKM theory and a stepladder model of energy transfer.

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2- 3-. , - , .

     

Ethylene hydroformylation over a nafion-supported rhodium catalyst

Ethylene hydroformylation over a Nafion-supported rhodium catalyst has been studied under atmospheric pressure in the temperature range of 100–135 °C, using the transient response method.

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, , 100–135°C, .

     

Kinetics of perborate oxidation of quinol

The perborate oxidation of quinol in aqueous acetic acid is first order with respect to perborate, zero order with respect to quinol, and first order with respect to H⁺. The oxidation is faster than H₂O₂ oxidation. Breakdown of protonated perboric acid is suggested as the rate-limiting step.

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, H⁺. . , , , .

     

Methanol-based synthesis of hydrocarbons on bifunctional Y-type zeolites

The directions of methanol conversion on Pt, Pd, Zn, Ni metals and Y zeolites and on bifunctional metal-Y-zeolite catalysts have been studied. The increase of the hydrogenation activity of bifunctional catalysts enhances the rate of methanol conversion and decreases the selectivity of hydrocarbon formation.

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- Y, - Y.

     

Homogeneous decomposition of formaldehyde induced by a carbon dioxide laser

The homogeneous pyrolysis of formaldehyde has been studied under laser heating. At temperatures of 950–1000 K H₂CO decomposition is shown to be a radical chain reaction. Methanol formation in formaldehyde pyrolysis is a homogeneous reaction.

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. , H₂CO 950–1000° . .

     

Studies on the Fe2(MoO4)3-V2O5 system

The phase equilibria established in solid state in the whole range of component concentrations in the Fe₂(MoO₄)₃-V₂O₅ system were studied by DTA and X-ray powder diffraction. This system is not a real two-component system.

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Zusammenfassung Im gesamten Konzentrationsbereich der Komponenten des Systems Fe₂(MoO₄)₃-V₂O₅ wurde das im festen Aggregatzustand festgestellte Phasengleichgewicht mittels DTA und Pulverröntgendiffraktionsverfahren untersucht. Dieses System ist kein wirkliches Zweikomponentensystem.

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F₂(₄)₃-V₂O₅ . , .

     

Double dimethylammonium sulphates of Tb,Dy, Ho,Er, Tm,Yb, Lu and Y

Double sulphates of rare earths with dimethylammonium, with empirical formula (CH₃)₂NH₂Ln(SO₄)₂·4H₂O (Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu and Y), were studied by means of thermogravimetry, derivative thermogravimetry and differential thermal analysis from 20 to 700°. Quantitative gravimetric analysis was used for the determination of rare earths and sulphate. The mechanism of thermal decomposition is also suggested.

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Zusammenfassung Doppelsulfate der seltenen Erden mit Dimethylammoniumionen der empirischen Formel (CH₃)₂NH₂Ln(SO₄)₂·4H₂O (Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu und Y) wurden mittels TG, DTG und DTA im Temperaturbereich von 20–700° untersucht. Die Seltenen Erden und Sulfat wurden gravimetrisch bestimmt. Ein Mechanismus der thermischen Zersetzung wird vorgeschlagen.

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, 20–700° (₃)₂N₂Ln(S₄)₂·4₂, Ln=Tb, Dy, , Er, Tm, Yb, Lu Y. . .

     

The measurement of meaningful activation energies

The uncertainty surrounding the significance of the measured kinetic parameters of solid state decomposition reactions is discussed briefly. Some suggestions are made about what precautions should be taken in order to favour the measurement of undistorted results. Some criteria are proposed for deciding whether a measuredE value can be considered to have its usual meaning. The results of a series of experiments aimed at measuring the activation energy of the decomposition of calcium carbonate using a variety of methods, sample sizes and experimental conditions are presented. These results are compared with results found in the literature and it is concluded that it is possible to measure a reproducible value forE and it is tentatively proposed that this value is meaningful in terms of the energy barrier model of chemical reaction kinetics.

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Zusammenfassung Die sich auf die Signifikanz gemessener kinetischer Parameter von Zersetzungsreaktionen fester Stoffe beziehende Unsicherheit wird kurz diskutiert. Es werden einige Vorschläge hinsichtlich der Vorkehrungen unterbreitet, die zu treffen sind, um unverfälschte Meßergebnisse zu erhalten. Einige Kriterien werden vorgeschlagen, die geeignet sind zu entscheiden, ob ain gemessenerE-Wert die übliche Bedutung hat. Ergebnisse einer Reihe von Experimenten werden angegeben, die ausgeführt wurden, um die nach verschiedenen Methoden, bei Anwendung unterschiedlicher Probenmengen und unter verschiedenen Versuchsbedingungen für die Aktivierungsenergie der Zersetzung von CaCO₃ erhaltenen Werte zu vergleichen. Es wird gefolgert, daß es möglich ist, den Wert vonE reproduzierbar zu messen, und versuchsweise vorgeschlagen, diesen Wert als sinnvoll für das Energiebarrierenmodell der chemischen Reaktionskinetik anzusehen.

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. , . , E . , , . . , .

     

Catalysis of thiophene hydrogenolysis by bimetallic sulfide catalysts of different compositions

The activity of sulfide catalysts M_I/SiO₂, M_I/WS₂, (M_I,W)/SiO₂ and (Ni,M_II)/SiO₂ (M_I is a first row transition metal, and M_II=Nb, Mo, W or Re) in the thiophene hydrogenolysis reaction has been studied. Activities of mono- and bimetallic catalysts are found to change in the same manner depending upon the nature of M_I. The formation of a sulfide bimetallic species (SBMS) is suggested.

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M_I/SiO₂, M_I/WS₂, (M_I,W)/SiO₂ (Ni, M_II)/SiO₂, M_I — , M_II–Nb, Mo, W, Re. - M_I. .

     

Kinetic studies of multi-step thermal degradations of copolymers or polymer mixtures

A kinetic analysis of multi-step thermogravimetric curves was developed for separation of overlapping decomposition steps to determine their individual reaction order, activation energy and weight loss. The method was applied in three instances: (a) separation of evaporation from decomposition for an isobutene-butadiene copolymer; (b) effects of drying conditions on the volatile content of a styrene-indene resin; (c) separation of dehydrochlorination from cyclodecomposition of poly(vinyl chloride).

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Zusammenfassung Eine kinetische Analyse von mehrstufigen thermogravimetrischen Kurven wurde entwickelt, um überlappende Zersetzungsstufen zu trennen, ihre individuellen Reaktionsordnungen, Aktivierungsenergien und Gewichtsverluste zu bestimmen. Die Methode wurde in drei Fällen eingesetzt: (a) Trennung der Verdampfung des Isobuten-Butadien-Kopolymers von der Zersetzung; (b) die Wirkung der Trocknungsbedingungen auf den Gehalt an flüchtigen Substanzen eines Styrol-Inden-Harzes; (c) Trennung der Dehydrochlorierung des Poly-Vinylchlorids von der Ringspaltung.

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Résumé On a mis au point une méthode d'analyse cinétique des courbes thermogravimétriques en plusieurs termes pour séparer les étapes de décomposition qui se chevauchent et déterminer pour chacune d'elles l'ordre de réaction, l'énergie d'activation et la perte de poids. On a utilisé cette méthode dans trois cas: a) pour distinguer l'évaporation de la décomposition du copolymère isobutène-butadiène, b) pour étudier l'influence des conditions de séchage sur la teneur en substances volatiles d'une résine styrène-indène, c) pour distinguer la déchlorhydratation du chlorure de polyvinyle de la décomposition du cycle.

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, , . : () -; () - ; () .

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Paper presented at the International Symposium on Macromolecular Chemistry, Budapest, 1969.     

Preparation,spectral and thermal studies of neodymium zirconyl oxalate hexahydrate

Neodymium zirconyl oxalate (NdZrOX) is prepared and characterized by chemical analysis and ir spectral studies. Its thermal decomposition has been investigated by using DTA, TG, DTG, X-ray diffraction and ir spectroscopy. On the basis of thermogravimetry and isothermal studies a probable mechanism for the decomposition is proposed. The decomposition proceeds mainly through three stages: i) dehydration between RT-413 K, ii) decomposition of oxalate between 413–943 K and iii) decomposition of the carbonate between 1028–1235 K to give a mixed oxide. The ir spectra and X-ray diffraction studies are made for identification of the intermediates. X-ray diffraction studies of the end product indicates that it belongs to cubic crystal system witha=11.520 Å.

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Zusammenfassung Neodymzirkonyloxalat (NdZrOX) wurde dargestellt und durch chemische Analyse und IR-spektroskopische Untersuchungen charakterisiert. Die thermische Zersetzung dieser Verbindung wurde mittels DTA. TG, DTG, Röntgendiffraktometrie und IR-Spektroskopie untersucht. Basierend auf Ergebnisse der Thermogravimetrie und isothermer Methoden wird ein möglicher Zersetzungsmechanismus vorgeschlagen. Die Zersetzung verläuft im wesentlichen über drei Stufen: i) Dehydratisierung zwischen Zimmertemperatur und 413 K, ii) Zersetzung des Oxalats zwischen 413 und 943 K und iii) Zersetzung des Carbonats zwischen 1028 und 1235 K unter Bildung eines Mischoxides. IR-spektroskopische und röntgendiffraktometrische Untersuchungen wurden zur Identifizierung der Zwischenprodukte ausgeführt. Die röntgendiffraktometrische Untersuchung des Endproduktes ergibt eine kubische Zelle mita= 11.520 Å.

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-. , , , . . , , : / 413 , / 413943 / 1028–1235 . - . - , =11.520 Å.

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One of the authors (VBR) is grateful to CSIR (India) for the senior research fellowship.     

Thermogravimetric characterization of Quayarah heavy crude oils

Five heavy crude oil samples from the Quayarah field were thermally evaluated using two modes of thermogravimetry (TG): dynamic and programmed TG with heating and hold-up periods at 350 and 550°. The light and medium volatility fraction (L+M) appeared directly proportional to the metal content. In contrast, the heavy fraction (H) (350–550°) was inversely proportional to the metal content. This contradiction was attributed to the autocatalytic degradation of some of the heavy fraction into lighter species, which upgrades the crude with respect to the (L+M) fraction at the expense of the heavy fraction. The crudes were identical with regard to the ratio (L+M) to (H+R), whereR=residue, as a consequence of their identical API gravity and sulphur contents.The rate of degradative volatilization of the heavy fraction was measured by DTG, which indicated a direct correlation with the vanadium content as regards the onset temperatures and the DTG peak maximum.

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Zusammenfassung Fünf vom Quayarah-Feld stammende schwere Rohöle wurden mittels dynamischer und programmierter TG mit konstanten Perioden bei 350 und 550 °C charakterisiert. Der Anteil der leicht- und mittelflüchtigen Fraktion (L+M) schien proportional, der der schwerflüchtigen Fraktion (H) (350 550°) dagegen umgekehrt proportional dem Metallgehalt zu sein. Dieser Widerspruch wurde dem autokatalytischen Abbau einiger der schwerflüchtigen Komponenten zu leichteren Spezies zugeschrieben, der zu einer Erhöhung des Anteils der (L+M)-Fraktion auf Kosten der schwerflüchtigen Fraktion führt. Die Rohöle waren wegen der gleichen API-Schwere und gleicher Schwcfclgehalle hinsichtlich des Verhältnisses von (L+M) zu (H+R) identisch (R=Rückstand). Die Geschwindigkeit der degradaliven Verflüchtigung der schweren Fraktion wurde mittels DTG gemessen, wobei sich eine direkte Korrelation zwischen dem Vanadingehalt einerseits und der Einsatztemperatur bzw. dem DTG-Peakmaximum andererseits ergab.

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350 550°. (+ ) , () (350–550°) — . , . + +, — , . . , , .

     

The thermal properties of some metal complexes of diethyldithiocarbamic acid new volatile metal chelates

The cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), silver(I) and mercury(II) complexes of diethyldithiocarbamic acid were prepared and their thermal properties determined by TG, DTA, and high temperature reflectance spectroscopy. It was found that the copper(II), nickel(II), and zinc(II) chelates were completely volatile and thus represent a new class of volatile metal chelates. Vapor pressure measurements were made on four of the metal complexes; heats of vaporization ranged from 9.3±0.2 kcal/mole for Na[Co(DDC)₃] to 24.2±0.6 kcal/mole for Zn(DDC)₂.

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Zusammenfassung Es wurden die Komplexe von Kobalt(II), Nickel(II), Kupfer(II), Zink(II), Cadmium(II), Silber(I) und Quecksilber(II) mit Diäthyldithiokarbaminsäure hergestellt und ihre thermischen Eigenschaften durch Thermogravimetrie, Differentialthermoanalyse und Hochtemperatur Reflexions Spektroskopie untersucht. Man fand, daß die Kupfer(II)-, Nickel(II)- und Zink(II)-Komplexe vollständig verflüchtigen. Sie stellen eine neue Sorte flüchtiger Metallchelate dar. Dampfdruckmessungen wurden an vier der Komplexe unternommen. Die Verdampfungswärmen liegen zwischen den Werten von 9.3±0.2 Kcal/Mol für Na[Co(DDC)₃] bis 24.2±0.6 Kcal/Mol für Zn(DDC)₂.

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Résumé On a préparé les complexes de cobalt(II), nickel(II), cuivre(II), zinc(II), cadrnium(II), argent(I) et mercure(II) avec l'acide diéthyle-dithiocarbaminique et étudié leurs propriétés thermiques par TG, ATD et spectroscopie de reflexion à haute température. On a trouvé que les complexes de cuivre(II), nickel(II) et zinc(II) volatilisent parfaitement; ils représentent une nouvelle sorte de chélates métalliques volatiles. On a fait des mesures de pression de vapeur sur quatre de ces complexes. Les valeurs des chaleurs de vaporisation s'étalent de 9.3±0.2 kcal/mole pour Na[Co(DDC)₃] jusqu'à 24.2±0.6 kcal/mole pour Zn(DDC)₂.

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[II], [II], [II], [II], [II], [I] [II] , . , [II], [II] — . ë -; 9,3±0,2 / Na[Co(DDC)₃] 24,2±0,6 / Zn[DDC]₂.

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The partial support of this work by the U. S. Air Force, Air Force Office of Scientific Research, through Grant No. AF-AFOSR 69-1620, is gratefully acknowledged. One of us (G. D'A.) wishes to thank the National Research Council of Italy, Rome, Italy, for financial support.     

Photooxygenation of 9-methyl-1,2,3,4-tetrahydrocarbazole: A kinetic study

The reaction of the singlet oxygen with 9-methyl-1,2,3,4-tetrahydrocarbazole has been undertaken to give a benzazonine derivative in good yield. Rose-bengal supported on an anionic resin was used as heterogeneous photosensitizing agent. Kinetic evaluation has been made for the additon of singlet oxygen to the indole ring at room temperature.

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9--1,2,3,4- . , , . .