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.

---

, , .

     

Thermal study of some sulphosuccinates

The thermal properties of some sulphosuccinates and their intermediates were studied by using combined dynamic thermal analysis and mass spectrometry. The temperature ranges were similar in the two methods, and a scheme of thermal decomposition of the compounds investigated was suggested. In the first temperature range of thermal decomposition of the sulphosuccinate a-rupture of the molecular ion occurs. In the second temperature range, the fragmentation proceeds in two directions: either-rupture of the ethoxylated nonylphenol, or-rupture of the acid residue of the sulphosuccinates.

---

Zusammenfassung Mittels einer Kombination von dynamischer Thermoanalyse und Massenspektroskopie wurden die thermischen Eigenschaften einiger Sulfosukzinate und deren Zwischenprodukte untersucht. Im ersten Temperaturbereich der thermischen Zersetzung des Sulfosukzinates findet eine-Spaltung des Molekülions statt. Im zweiten Temperaturbereich tritt auch ein alternativer Fragmentierungsweg auf: eine-Spaltung des Säurerestes des Sulfosukzinates.

---

- . . - -. : - - .

     

Physico-chemical properties of silica-supported vanadium oxide catalysts

- . TiO₂ ZnO. - CO₂ H₂O. — .

---

The effect of visible light on propane and n-butane oxidation has been sutied on a seires of metal oxides. TiO₂ and ZnO have been found to exert a photocatalytic effect. On TiO₂, propane and n-butane are oxidized to CO₂ and H₂O. On ZnO as catalyst, partial oxidation products, aldehydes and ketones, are formed.

     

Palladium/sepiolite systems as hydrogenation catalysts, III. Hydrogenation of variously substituted olefins

The application of a Spanish sepiolite variety known as Pansil (commercialized by Tolsa S.A.): as a Pd support in the reduction of variously substituted carbon-carbon double bonds, both with gaseous hydrogen and by hydrogen transfer with cyclohexene as donor is described.

---

, Pansil, Tolsa S.A., Pd C=C, , ( ).

     

CeO2-supported nickel catalysts. Evidence of a strong metal-support ineraction

An increase of the reduction temperature of a Ni/CeO₂ solid results in a continuous decrease of the catalytic activity toward C₂H₆ hydrogenolysis and of the quantity of adsorbed H₂. O₂ treatments with subsequent reduction at low temperature restore a part of the initial properties. This behavior, typical of a strong metal support interaction, is similar to that of Ni/TiO₂, Ni/SiO₂ and Ni/ZrO₂ solids and shows that the SMSI phenomenon is general.

---

Ni/CeO₂ C₂H₆ H₂. . , (), Ni/TiO₂, Ni/SiO₂ Ni/ZrO₂ , .

     

Study of nitric oxide interaction with the Pt(100) surface by electron energy loss spectroscopy

The adsorption and dissociation of nitric oxide on the Pt(100) surface have been studied using Electron Energy Loss Spectroscopy.

---

Pt(100).

     

Effect of orbital-rotational coupling on the rate of ion-dipole capture at extremely low temperatures

The rate of the ion-dipole capture at very low temperatures or energies has been examined using the Statistical Adiabatic Channel model.

---

- .

     

The application of thermoanalytical methods in the investigation of biological substances

The equilibria and thermodynamics of a number of naturally occuring isolated compounds (e.g. proteins, amino acids, carbohydrates) have recently been studied in several laboraties in different temperature ranges, and thermoanalytical methods have been used to study structural changes of biological materials, among them human tissues.In our investigations we succeeded in appling the derivatograph for the assay of glycosaminoglycans and for the characterization of the stability of crosslinked proteins in intact human and animal tissues. By means of this method age-related and pathological changes and repair reactions were studied in various connective and vascular tissues.Other temperature-dependent techniques (DSC, polarizing microscopy) were used successfully in another series of experiments. Alterations in the characteristic order-disorder transition temperatures of human serum lipoproteins could be demonstrated in pathological conditions; the altered physical structure of lipoproteins might give an additional explanation to the assumed mechanism of different metabolic disorders.

---

Zusammenfassung Die Gleichgewichte und die Thermodynamik einer Reihe von natürlich vorkommenden isolierten Verbindungen (z. B. Proteine, Aminosäuren, Kohlenhydrate) wurden in verschiedenen Laboratorien in verschiedenen Temperaturbereichen untersucht. Hierbei wurden thermoanalytische Methoden zum Studium der Strukturänderungen von biologischem Material, u. a. von menschlichem Gewebe, eingesetzt.In unseren Untersuchungen gelang es den Derivatographen zur Prüfung von Glycosaminoglycanen und zur Charakterisierung der Stabilität quervernetzter Proteine in intakten menschlichen und tierischen Geweben einzusetzen. Durch diese Methode wurden altersbedingte und pathologische Änderungen sowie Reaktionen zur Wiederherstellung in verschiedenen Binde und Vasculärgeweben studiert.Andere temperaturabhängige Techniken (DSC, Polarisationsmikroskopie) wurden in anderen Versuchsserien mit Erfolg eingesetzt.

---

, . , , , , . . , . .

---

---

Plenary lecture     

Kinetic studies of ozonation of polyhydric alcohols

Kinetic studies of the oxidation of polyhydric alcohols by ozone-oxygen mixtures in aqueous solutions at 284–302 K indicate that the second-order effective rate constantk decreases with increasing substrate concentration.

---

- 284–302 . , .

     

Complexes of amic acids with polar aprotic solvents. VI. System of hydrogen-bonds in complexes of amic acids and polyamic acids with amide solvents

It has been established through X-ray analysis of complexes of pyromellitedianylic acid with amide solvents that the type of the system of hydrogen-bonds and the solvate structure depend on the nature of these solvents. It is shown for solvates of poly(4,4-oxydiphenylene)pyromellite amic acid that mass spectrometric thermal analysis (MTA) may be used for the investigation of hydrogen-bonds formed in solid polyamic acid films. The MTA data may be employed to establish the mechanism of the effects of additives catalysing the solid-phase cyclodehydration of polyamic acids.

---

Zusammenfassung Durch röntgenanalyse von Komplexen von Pyromellit-dianilicsäure mit Amidlösungsmitteln wurde festgestellt, daß der Typs des Systems der Wasserstoffbindungen und die Solvatstruktur von der Natur dieser Lösungsmittel abhängt. Für Solvate der Poly-(4,4-oxydiphenilen) pyromellit-amicsäure wird gezeigt, daß die massenspektrometrische thermische Analyse (MTA) zur Untersuchung von in festen Polyamicsäurefilmen ausgebildeten Wasserstoffbindungen herangezogen werden kann. Die MTA-Daten können zur Ermittlung des Wirkungsmechanismus von die Festphasencyclodehydratisierung von Polyamicsäuren katalisierenden Additionen herangezogen werden.

---

, . , (4,4-) , , o , , .

     

Hreels studies of Hads effect on NO adsorption on Pt(111)

HREELS studies of NO molecular adsorption on clean and hydrogen covered Pt(111) have revealed that a reversible transition between bridge (₁) and on-top (₂) states of NO_ads is realized in the (NO+H₂)/Pt(111) system. In the presence of H_ads the adsorption of NO in the ₁ state is inhibited and the main state of NO_ads is ₂. Upon heating the layer (₂-NO_ads+H_ads) hydrogen desorption is accompanied by on-top to bridge state conversion.

---

NO Pt(III). , (NO+H₂)/Pt(III) (₁) (₂) NO. H NO ₁ , , ₂ NO. (₂-NO+H) NO .

     

Retrieval of thermodynamic properties of M(OH)2 (M=Mn,Ni and Cd) phases from hydrothermal phase equilibria of MO-H2O systems

The standard thermodynamic properties of M(OH)₂ (M=Mn, Ni and Cd) solid phases have been retrieved using a graphical approach based on the already reportedP vs. T curves obtained from hydrothermal studies of MO-H₂O systems. This approach avoids the use of heat capacity effects. The values retrieved by this modified approach are in good agreement with the calorimetric values.

---

Zusammenfassung Basierend auf unlängst beschriebenen, aus hydrothermischen Untersuchungen von MO-H₂O Systemen gewonnenenp-T Kurven wurden mittels einer graphischen Näherung die thermodynamischen Standardeigenschaften von M(OH)₂ Festphasen (M=Mn, Ni und Cd) bestimmt. Dieses Verfahren umgeht den Gebrauch von Wärmekapazitätseffekten. Die durch dieses modifizierte Verfahren erhaltenen Werte stehen in guter Übereinstimmung mit den kalorimetrischen Werten.

---

- , O-H₂O, M(OH)₂, M=, . . .

---

---

The authors express their grateful thanks to Prof. V. Venkatachalapathy, Director of the Minerological Institute, for his encouragement during the course of this work.     

Intermediates of homogeneous deuterium exchange in alkanes catalyzed by Pt(II)

The rate constants and distribution of deuterated products of the H-D exchange in alkanes (C₁–C₈) have been measured for aqueous solutions of K₂PtCl₄. The reaction involves the intermediate formation of alkyl, 1,1-(carbene). 1,2-(olefin), 1,3-(cyclopropane) and 1,4-(cyclobutane) type hydrocarbon complexes. The selective attack of Pt(II) on the primary, secondary and tertiary C–H bonds in alkanes (110) is due to the predominance of steric over polar effects.

---

H-D (C₁–C₈) K₂PtCl₄ , , 1,1-(), 1,2-(), 1,3-() 1,4-() . Pt(II) ., ., . C–H (110) .

     

Effect of traces of water vapor on the rate of ammonia decomposition on polycrystalline platinum

The influence of small (lower than 0.02) molar fractions of water on the rate of ammonia decomposition on platinum wires was studied for ammonia pressures varying between 6.7 and 93.3 kPa and temperatures between 800 and 1700 K. The presence of water strongly inhibited the rate of reaction in all experiments.

---

( 0,02) , 6,7 93,3 , 800 1700 K. .

     

Kinetic studies of Pt/Al2O3 catalyst pellets with nonuniform activity

Catalysts with nonuniform distribution of the catalytically active component (Pt) over their porous support (Al₂O₃) have been studied. A nonuniform activity distribution changes not only the reaction rate but also the kinetics can be different on these catalysts.

---

(Pt) (Al₂O₃). , , .

     

Heterogeneous decay of fluorine atoms

The probability of decay of fluorine atoms on the surface of molybdenum glass, quartz, Teflon, copper, nickel, gold and on aluminium alloy at 20–300 °C has been determined.

---

, , , , , 20–300 °C.

     

Thermal degradation of polymers and flame retardants

We have carried out simultaneous Thermal Analysis/Mass Spectrometry by use of a Netzsch STA 429 Thermal Analyzer (TG-DTG-DTA) combined with a Balzers QMG 511 quadrupole Mass Spectrometer.The combined apparatus is interfaced to a Digital Equipment PDP 11/23+ microcomputer. The complete set of the TA/MS data obtained simultaneously after each run results in detailed information about the thermal degradation of a sample material in general and in addition about the structure-temperature dependent fragmentation. Experiments by use of a Perkin-Elmer DSC 7 Thermal Analysis Station leads to quantitative determination of the characteristic data.

---

Zusammenfassung Es wurden simultane thermoanalytische — massenspektrometrische Untersuchungen mit Hilfe einer Gerätekombination Netzsch STA 429 (Thermowaage) und Balzers QMG 511 (Quadrupol Massenspektrometer) durchgeführt. Dieses Kopplungssystem ist mit einem Digital Equipment PDP 11/23+ Microcomputer verbunden. Der komplette Datensatz, der aus einer TA/MS Messung erhalten wird, charakterisiert in sehr detaillierter Weise das thermische Abbauverhalten von Substanzen und gibt Aufschluß über die temperatur-struktur-abhängige Fragmentierung der Verbindungen.

---

, /-/ - 511. 11/23. /MC, , - . , - 7, .

     

Consecutive hydrogenation of pseudoionon. Application of diffusion kinetic model to predict experimental reactor operation

A method for the calculation of fixed catalyst bed reactors by using a diffusion kinetic model is suggested. Correlation between calculated curves for the time distribution of the reaction mixture composition and experimental data is given.

---

=qo . .

     

Simulation thermique d'experiences d'analyse thermique differentielle

The numerical modelling of casting pieces needs a knowledge of the physicochemical features of the alloys (cast iron, superalloys): enthalpic release versus temperature in the solidification range. The use of differential thermal analysis is proposed for estimation of the enthalpic release. The thermal modelling of the DTA cell gives the enthalpic release versus temperature relation. Moreover, the simulation shows that large temperature variations (about 10 °C) occur in the sample during the first stage of solidification, which makes interpretation of the solidification path very difficult.Quenching from different temperatures during DTA experiments was also simulated.

---

Zusammenfassung Die numerische Modellierung von Gußstücken erfordert die Kenntnis physikalisch-chemischer Kennwerte der Legierungen (Gußeisen, Superlegierungen), nämlich der Enthalpieänderung in Abhängigkeit von der Temperatur im Erstarrungsbereich. Die DTA-Methode wird zur Bestimmung der Enthalpieänderung in Vorschlag gebracht. Die thermische Modellierung der DTA-Zelle schließt die Temperaturabhängigkeit der Enthalpieänderung in sich ein. Darüber hinaus ergibt die Simulierung, daß große Temperaturänderungen (etwa 10°) in der Probe während des ersten Stadiums der Erstarrung auftreten, die die Interpretation des Erstarrungsvorganges erschweren. Abschrecken bei verschiedenen Temperaturen wurde in den DTA-Experimenten ebenfalls simuliert.

---

- ( , ), . . . , , ( 10 °C). . .