Calorimetric studies of aluminosilicate catalysts heats and entropies of cumene adsorption on cation substituted metakaolinite

Differential heats of cumene adsorption at 293 K on Ca-, Sr- and Ba-substituted metakaolinites at surface coverages up to 0.1 have been measured on a Calvet microcalorimeter. The presence of two energetically different adsorption centers are shown to be determined by the nature of the exchanged cation; the adsorption heats decrease in the sequence Ba, Sr, Ca, Mg.

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293 Ca-, Sr, Ba- 0.1. . , Ba, Sr, Ca, Mg.

     

Reaction of ammonium sulphate with aluminium oxide

The reaction between ammonium sulphate with aluminium oxide was studied. It was confirmed by X-ray diffraction and chemical analysis that three intermediate reaction products, (NH₄)₃Al(SO₄)₃, NH₄Al(SO₄)₂ and Al₂(SO₄)₃, are formed. The thermal decompositions of these three compounds were carried out. It has been shown that the same rate law is valid for them. The activation energies for (NH₄)₃Al(SO₄)₃, NH₄Al(SO₄)₂ and Al₂(SO₄)₃ are 95.9, 177.9 and 291.0 kj/mol, respectively.

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Zusammenfassung Die Reaktion von Ammoniumsulfat mit Aluminiumoxid wurde untersucht. Durch Röntgendiffraktion und chemische Analyse wurde bestätigt, daß drei Zwischenprodukte (NH₄)₃Al(SO₄)₃, NH₄Al(SO₄)₂ und Al₂(SO₄)₃ gebildet werden. Die thermische Zersetzung der drei Verbindungen wurde durchgeführt. Es wurde gezeigt, daß für alle drei dasselbe Geschwindigkeitsgesetz Gültigkeit hat. Die Aktivierungsenergien für (NH₄)₃Al(SO₄)₃, NH₄Al(SO₄)₂ und Al₂(SO₄)₃ sind 95.9, 177.9 und 291.0 kJ/Mol.

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. - : (NH₄)₃Al(SO₄)₃, NH₄Al(SO₄)₂ Al₂(SO₄)₃. , , . (NH₄)₃Al(SO₄)₃, NH₄Al(SO₄)₂ Al₂(SO₄)₃, , 95.9; 177.9 291.0 . ^–1.

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The authors are grateful to Dr. H. Osada and Mr. H. Nakamura, Department of Environmental Engineering, Kyushu Institute of Technology, for their helpful discussions.     

The compensation effect: A fact or a fiction

In this article, the facts and fictions surrounding the compensation effect is explored. False compensation effect occurs mainly due to: propagation of computational and experimental errors resulting in inaccurate estimates of the Arrhenius parameters; and, the natural compensation between InA andE. Since Arrhenius parameters are sensitive to errors in temperature; the errors due to uncertainty in temperature should be minimized to eliminate false compensation effect. Increasing the experimental temperature range is helpful in minimizing errors due to uncertainty in temperature. A point of concurrence in a plot of Ink and 1/T establishes the occurrence of true compensation effect. True compensation effect has been shown to be a useful tool in chemical research for: identifying the governing reaction mechanism; predicting the effects of various reaction parameters; and, correlating and reducing experimental data.

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Zusammenfassung In dieser Mitteilung werden Fakten und Vorstellungen betreffs des Kompensationseffektes untersucht. Falsche Kompensationseffekte werden hauptsächlich verursacht durch: eine ungenaue Ermittlung der Arrheniusparameter durch die Fortpflanzung von rechnerischen und experimentellen Fehlern sowie dem natürlichen Kompensationseffektes zwischen InA undE. Das Arrheniusparameter gegenüber Fehler im Temperaturwert sehr empfindlich sind, sollten Temperaturungenäuigkeitsfehler zur Vermeidung eines falschen Kompensationseffektes minimalisiert werden. Zur Verminderung der aus der Temperaturungenauigkeit resultierenden Fehler ist es von Nutzen, den Temperaturbereich des Experimentes zu erweitern. Ein wahrer Kompensationseffekt wird durch einen Schnittpunkt in einem Ink-1/T Diagramm angezeigt. Es wird gezeigt, daß der wahre Kompensationseffekt ein nutzvolles Mittel in der chemischen Forschung darstellt: zur Feststellung des dominierenden Reaktionsmechanismus, zur Vorhersage der einflüsse verschiedener Reaktionsparameter und zur Aufarbeitung und Schlußfolgerung von bzw. aus experimentellen Daten.

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, . , , lnA E. , , . . Ink-1/T . , , , .

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The author would like to thank the reviewer for his constructive criticisms.     

Effect of the experimental conditions on the thermooxidative behaviour of vegetable oils

The thermooxidative behaviour of sunflower and rapeseed oils has been investigated by means of a derivatograph, using both dynamic and static (isothermal) temperature programs. The aim was to find the optimum experimental conditions for studying the oxidative stability of edible oils, in order to determine their storability. A novel method has been developed for the rapid indication of stability by modelling the oxidative changes under isothermal conditions.

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Zusammenfassung Das thermooxidative Verhalten von Sonnenblumen- und Rapsöl wurde mittels eines Derivatographen unter Einsatz dynamischer und statischer (isothermer) Temperaturprogramme untersucht. Der Zweck der Arbeit war die optimalen Versuchsbedingungen zur Bestimmung der Oxidationsstabilität von Speiseölen zu finden um ihre Lagerfähigkeit zu bestimmen. Eine neue Methode zur schnellen Ermittlung der Stabilität wurde mittels Modellierung der oxidativen Änderungen unter isothermen Bedingungen erarbeitet.

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Résumé On a étudié l'oxydabilité thermique des huiles de tournesol et de colza, à l'aide d'unDerivatigraph et en utilisant des programmes de température dynamiques et statiques (isothermes). Le but du travail était de trouver les conditions d'expérience les mieux adaptées à l'étude de la résistance à l'oxydation des huiles alimentaires afin de déterminer les conditions de leur stockage. On a mis au point une nouvelle méthode qui indique rapidement la stabilité de l'huile en reproduisant les changements d'oxydation en conditions isothermes.

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, ( ) . , , . .

     

Kinetic equations of isotope transfer by elementary reaction

On the basis of matrices of transfer of atoms kinetic equations of isotope transfer between the components participating in elementary reactions have been derived.

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, .

     

Applications of evolved gas analysis to the study of inorganic materials and processes

The value and versatility of evolved gas analysis (EGA) are described by the use of selected recent examples. Three particular attributes of EGA methods are stressed. The first, specificity, reveals the frequent necessity of using EGA to substantiate conclusions based upon other thermal analytical techniques e.g. thermogravimetry (TG) or differential thermal analysis (DTA). To this end, the weaknesses of other thermal analytical techniques for the analysis of asbestos is reveladed by EGA. However, because of EGA's specificity it could be used for this purpose. Second, sensitivity, is demonstrated by use of mass spectrographic EGA techniques to study the kinetics of the early stages for the thermal decomposition of InP. This is further illustrated by qualitative assessments of the effects of various films in contact with the InP upon its thermal decomposition. A third advantage of EGA, insensitivity to experimental perturbations arising from an external magnetic field gradient, allows for its use to study the effects of such field gradients with less ambiguity than occurs with TG or DTA. This is shown for studies of the reduction of NiO, Fe₂O₃, and Co₃O₄ by H₂.

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Zusammenfassung Die Bedeutung und die Vielseitigkeit der EGA wird anhand ausgewählter neuerer Beispiele beschreiben. Drei besondere Merkmale der EGA-Methoden werden hervorgehoben. Die erste, die Spezifität, wird der häufigen Notwendigkeit zur Anwendung der EGA gerecht, um auf andere thermische Analysentechniken, z.B. auf TG oder DTA beruhende Schlussfolgerungen zu stützen. Dies wird demonstriert, indem gezeigt wird, dass die EGA die Unzulänglichkeiten anderer thermischer Verfahren zur Analyse von Asbest in Erscheinung treten lässt und infolge ihrer Spezifität für diesen Zweck geeignet ist. Das zweite Merkmal, die Empfindlichkeit, wird durch Anwendung der massenspektrographischen EGA-Technik zur Untersuchung des frühen Stadiums der thermischen Zersetzung von InP demonstriert. Dies wird weiter durch qualitative Beurteilung der Wirkungen von verschiedenen in Kontakt mit dem InP befindlichen Filmen auf dessen thermische Zersetzung illustriert. Ein dritter Vorteil der EGA is deren Unempfindlichkeit gegenüber von äusseren magnetischen Feldgradienten herrührenden experimentellen Störungen, wodurch diese Methode bei der Untersuchung der Wirkungen solcher Feldgradienten eindeutigere Ergebnisse als die TG oder DTA liefert. Dies wird anhand von Untersuchungen der Reduktion von NiO, Fe₂O₃ und Co₃O₄ mit H₂ gezeigt.

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//, . , , , : , , . . , - InP. , In P . , . . , .

     

Temperature-programmed desorption of hydrogen from Fe?Ni/Al2O3 catalysts

The aim of this paper is to investigate temperature activated hydrogen adsorption on Fe–Ni/Al₂O₃ catalyst and for the sake of comparison also on monometallic systems Fe/Al₂O₃ and Ni/Al₂O₃.

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- Fe–Ni/Al₂O₃ , , Fe/Al₂O₃ Ni/Al₂O₃.

     

Ammonia adsorption on the surface of Ni(II)-, Cu(II)-and Co(II)-phthalocyanine

Ammonia adsorption on the surface of Ni(II)–, Cu(II)- and Co(II)-phthalocyanine has been studied by means of reflection spectroscopy. Ammonia bonds to the metal ions in the surface layers of phthalocyanines preferably in octahedral coordination. In the case of Co(II)-phthalocyanine the trivalent state of cobalt is stabilized. Close similarity between coordination in liquid phase and adsorption on the surface is observed.

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- , , . , - . Co (II)- . .

     

Effect of the nature of carrier on dinitrogen fixation by supported titanium complexes

Cyclopentadienyltitanium (IV) complexes supported on Al₂O₃, SiO₂ and MgO reduced with BuLi were tested in dinitrogen fixation at room temperature under normal pressure. Only the system supported on Al₂O₃ is active in this reaction.

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- (IV), Al₂O₃, SiO₂ MgO, BuLi, . Al₂O₃.

     

Aniline hydrogenation in the presence of alumina-supported rhodium under hydrogen pressure

Aniline hydrogenation over 5% Rh/Al₂O₃ in water and an universal queous buffer has been studied at temperatures of 323–363 K and pressures of 2.02–10.10 MPa.

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5% Rh/Al₂O₃ 323–363 K 0,5–10,10 .

     

Thermodynamic study of solvent extraction of monovalent metal picrates with benzo-18-crown-6 into chloroform

Thermodynamic parameters (H _ex ⁰ and S _ex ⁰ ) for the overall extractions of monovalent metal (Na, K, Rb, and Tl) picrates with benzo-18-crown-6 (B18C6), and those (H _D,L ⁰ and S _D,L ⁰ ) for the distribution of B18C6 were determined between chloroform and water. All the extracted B18C6 complexes were l:1:1 complexes (B18C6:metal ion: picrate anion). The H _ex ⁰ and S _ex ⁰ values for all the metals are negative. Every extraction of the metal picrate with B18C6 is completely enthalpy driven. The H _D,L ⁰ and S _D,L ⁰ values of B18C6 are both positive, and the partition of B18C6 is entirely entropy driven. Enthalpy (H _ex,ip ⁰ ) and entropy changes (S _ex,ip ⁰ ) for ion-pair extractions of B18C6-metal ion complexes with picrate anions were calculated. All the H _ex,ip ⁰ and S _ex,ip ⁰ values are negative, and the ion-pair extractions are completely enthalpy driven.     

Promoting effect of sodium on catalytic and adsorption properties of Fe?Mn catalysts for CO hydrogenation

It has been established that alkali metal (sodium) additives affect both texture and adsorption properties of Fe–Mn catalysts for olefin synthesis thus promoting their catalytic properties.

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() , Fe–Mn , .

     

On the stability of substituted 1,2-diazaallyl radicals

The heats of formation of fully optimized methyl-ethyl-and 2-propyl-substituted 1,2-diazaallyl radicals and their parent compounds have been calculated at the level of semiempirical quantum-chemical methods (MNDO-HE, AM1-HE). The resonance energies and the stabilization energies were found to be 30–60 kJ mol^–1 and around 60 kJ mol^–1, respectively. From AM1-HE calculations, the group values _fH^°[C–(N_A)(H₂)]=90.4 kj mol^–1, _fH^°[C–(N_A)(C)(H)]=94.8 kj mol^–1 were obtained.

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-, - 2- 1,2- - (MNDO-HE, AM1-HE). 30–60 /, 60 /. AM1-HE _fH^°[C–(N_A)(H₂)]=90,4 ͆/, _fH^°[C–(N_A)(C)(H)]=94,8 ͆/.

     

Modification of preparation technique for highly dispersed Ni/γ?Al2O3 catalysts

Highly dispersed Ni/–Al₂O₃ catalysts have been prepared by the method of double impregnation. The application of ethylenediaminetetraacetic acid (H₄Y) as a chelating agent for activation of the -Al₂O₃ support enables us to prepare highly dispersed Ni/Al₂O₃ catalysts. The use of this chelating agent according to the described modification of the impregnation technique results in the highest dispersity of the metal component in the catalysts obtained.

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Ni/-Al₂O₃ . (H₄Y) -Al₂O₃ Ni/Al₂O₃ . , .

     

Determination of metal particle sizes in supported catalysts by small-angle X-ray scattering technique

Pt/SiO₂ catalysts have been studied by a small-angle X-ray scattering technique without commonly practiced packing of the carrier pores. The obtained Pt particle sizes are in good agreement with chemisorption and electron microscopy data.

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Pt/SiO₂ . Pt .

     

The role of excited states in the photolysis of n-butyraldehyde, II. Intersystem crossing quantum yields

Singlet triplet intersystem crossing quantum yields were determined for n-butyraldehyde, using the photosensitized cis-trans isomerization of piperylene to monitor the process. At room temperature and 313 nm, 0.58±0.05 and 0.72±0.05 were obtained for the triplet yield in the vapor phase and in isooctane, respectively.

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- - - . 0,58±0,05 0,72±0,05 313 .

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For Part I, see Ref. /1/     

Das Verhalten des α-(2-Methylmercapto-äthyl)-acetessigesters unter den Bedingungen der Schmidt-Reaktion

Zusammenfassung -(2-Methylmercapto-äthyl)-acetessingester (IV) reagiert mit Stickstoffwasserstoffsäure unter den Bedingungen derSchmidt-Reaktion zum -Methylsulfimino--acetylaminobuttersäureäthylester (VII), dessen Verseifung Methioninsulfoxyd (VIII) ergibt.Aminsäuren. Mitteilung III.     

The consistency of repeated H2?O2 titration cycles on supported Pt catalysts

H₂ and O₂ uptakes at 296 K on a Pt/Al₂O₃ catalyst remained constant during repeated H₂–O₂ titration cycles conducted in a high vacuum adsorption system. Previously reported variations in these uptakes are attributed to adsorption of contaminants during desorption conditions. Also, it was found that nearly 40% of the H₂ adsorbed could be removed by degassing at 296 K for 1 hr.

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H₂ O₂ 296 Pt/Al/₂O₃ H₂–O₂, . . , 40% H₂ 1 296 .

     

2-Amino-4-[2-(5-nitro-furyl)vinyl]thiazole and its derivatives

The reactions of 4-bromo-1-(5-nitro-2-furyl)but-1-en-3-one and its 2-methyl and 2-chloro derivatives with thiourea and its N-allyl and N-phenyl derivatives have yielded 2-amino-4-[-5-nitro-2-furyl)-vinyl]thiazole and its - and N-substituted derivatives. 2-Amino-4-[-(5-nitro-2-furyl)vinyl]thiazole and its -methyl derivative have also been prepared by the direct reaction of the corresponding , -unsaturated ketones with bromine and an excess of thiourea in chloroform, as was shown by a comparison of UV spectra. A series of N-acyl derivatives of the aminothiazoles has been obtained. UV and IR spectra are given.