Changes in the catalytic properties of a multicomponent molybdenum catalyst under vibro-fluidized catalyst bed conditions

Activation effect of oxidative dehydrogenation of butene-l on a multicomponent molybdenum catalyst at various temperatures has been studied by pulse and flow techniques. It is shown that under vibrofluidization not only reactive but also adsorption properties of the catalyst surface change. Oxygen consumption in the reaction process has been examined.

---

-1 . , , . .

     

Influence of thermal and hydrothermal activation on the adsorptive, acidic and catalytic properties of high-silica zeolites

Influence of HS-zeolite calcination up to 1023 K in air and steam on its adsorptive, acidic and catalytic properties in n-hexane cracking has been studied.

---

- 1023 , -.

     

Catalytic activity of perovskite-type oxides LaMeO3

Catalytic activities for CO oxidation of a series of LaMeO₃(Me³⁺=V³⁺, Cr³⁺, Mn³⁺, Fe³⁺, Co³⁺, Ni³⁺) perovskite-type oxides were measured. Maxima for Mn³⁺ and Co³⁺ were found. The relation between local symmetry of solid surfaces and chemisorption and catalysis is discussed.

---

, LaMeO₃ (Me⁺³=V⁺³, Cr⁺³, Mn⁺³, Fe⁺³, Co⁺³, Ni⁺³) CO. Mn⁺³ Co⁺³. , .

     

Kinetics of the vapor-phase oxidation of o-xylene over a vanadium oxide catalyst

(Pt–Sn)/Al₂O₃. , , , , .

---

The catalytic and adsorption properties of the (Pt–Sn)/Al₂O₃ system have been studied. The results of benzene hydrogenation, cyclohexane dehydrogenation and temperature-programmed hydrogen desorption show that the introduction of tin into the Pt/Al₂O₃ catalyst significantly changes the dispersity and electronic state of supported platinum.

     

Application of thermal analysis for investigations of polymer powders for coatings

Polypropylene coatings obtained by the fluidized bed method were investigated. It was proved that the application of thermal analysis methods for their characterization gave many useful data, as a consequence of the similar conditions of thermal measurements and plastics powder processing. Significant correlations were found between the thermal properties and the standard coating poperties.

---

Zusammenfassung Durch Fluidisationsverfahren erhaltene Polypropylenbeschichtungen wurden untersucht. Es wurde festgestellt, daß infolge der ähnlichen Bedingungen von thermischen Messungen und Plastpulverisierungsverfahren die Anwendung von thermischen Untersuchungsmethoden zu deren Charakterisierung viele nützliche Angaben liefern. Es konnten eindeutige Beziehungen zwischen thermischen Eigenschaften und Standardbeschichtigungseigenschaften gefunden werden.

---

, . , , . .

     

Catalytic properties of some copper alloys in oxidative dehydrogenation of methanol

It has been established that among the copper alloys examined the most interesting catalytic properties are observed for tin-phosphorus bronze. It yields small amounts of hydrogen and carbon oxides and has a high selectivity to formaldehyde in the overall alcohol conversion, which is typical of pure copper.

---

. - , , .

     

Influence of the crystallite size of platinum on the course of hydrogenolysis and isomerization of n-butane over Pt/Al2O3 catalysts

The effect of platinum dispersity on the rate, selectivity and activation energy of hydrogenolysis and isomerization of n-butane has been studied. Maximum rates of n-butane hydrogenolysis and isomerization were observed at platinum crystallite sizes of 1.7–4.0 nm. In the same range of Pt crystallite size the activation energy of the process shows a clear minimum.

---

, 1,7–4,0 , , . Pt. Pt 3 .

     

Excess enthalpies in pyridine base-methanol systems

The excess enthalpy of mixing versus composition was studied at 293.15 K and 303.15 K for some binary mixtures of methanol with pyridine bases. The results are presented in Tables.

---

Zusammenfassung Der Zusammenhang zwischen Mischungsenthalpie und Zusammensetzung wurde bei 293.15 K und 303.15 K an einigen Binärsystemen von Methanol mit Pyridinbasen untersucht. Die Ergebnisse werden in Tabellen aufgeführt.

---

Résummé La variation de l'enthalpie de mélange en fonction de la composition a été étudiée à 293.15 K et 303.15 K dans quelques mélanges binaires de méthanol et de pyridine base. Les résultats sont présentés sous forme de tableaux.

---

293.15 303,15 . .

     

ESR studies of benzene interaction with the surface of Mo?Ti oxide catalysts

It has been established that in benzene interaction with Mo–Ti oxide catalysts stabilization of Mo⁵⁺ ions in the form of (MoO)³⁺ takes place due to formation of oxidized form of benzene, which leads to one-electron reduction of surface ions.

---

Mo⁵⁺ (MoO)³⁺ Mo–Ti , , .

     

Crystallisation behaviour and mechanical properties of HDPE/EPDM blends

The crystallisation behaviour of binary blends of high density polyethylene (HDPE) and ethylene-propylene-diene tercopolymer (EPDM) was investigated using differential scanning calorimetry (DSC) and wide angle X-ray diffraction studies (WAXS). The rate of crystallization and nucleation of HDPE was influenced by the addition of EPDM. The% crystallinity (WAXS) increased up to 25% (w/w) addition of EPDM to HDPE. A significant improvement in tensile and impact properties was observed upon addition of EPDM to HDPE.

---

Zusammenfassung Mittels Differential-Scanning-Kalorimetrie (DSC) und Weitwinkelröntgendiffraktion (WAXS) wurde das Kristallisationsverhalten von binären Gemischen aus hochverdichtetem Polyäthylen (HDPE) und Äthylen-Propylen-Dien Trikopolymer (EPDM) untersucht. Die Geschwindigkeit von Kristallisation und Keimbildung von HDPE wird durch Zusatz von EPDM beeinfluß. Die prozentuelle Kristallinität wuchs bis zu einer Zugabe von 25 Gewichtsprozenten EPDM zu HDPE an. Bei Zusatz von EPDM zu HDPE konnte eine eindeutige Verbesserung der Zug- und Stoßfestigkeitseigenschaften festgestellt werden.

---

() -- (). . 25 .%. .

     

A systematic theory of one-cell differential thermal analysis

The mathematical theory is developed for heat transfer in the cells of DTA instruments with no temperature gradient. Equations are derived for the various portions of the differential curve. The concepts of real and hypothetical base lines are introduced and rules are formulated for plotting them. Three methods are proposed for processing the curves, with and without the introduction of base lines. The physical meanings of the geometrical elements of the thermal curves and their relationship with the experimentally determined thermal quantities are elucidated. Equations in differential and integral forms are derived for the base line of the cell and the base line of the reaction.

---

Zusammenfassung Eine mathematische Theorie für den Wärmeübergang in Zellen von DTA-Geräten ohne Temperaturgradient wird entwickelt. Für die einzelnen Abschnitte der differentiellen Kurve werden Gleichungen abgeleitet. Das Konzept der reellen und hypothetischen Grundlinien wird eingeführt und Regeln für deren Konstruktion werden aufgestellt. Drei Methoden zur Darstellung der Kurven mit und ohne Einführung der Grundlinien werden vorgeschlagen. Die physikalische Bedeutung der geometrischen Elemente der thermischen Kurven und deren Beziehung zu den experimentell bestimmten thermischen Größen werden klargestellt. Für die Grundlinie der Zelle und für die der Reaktion werden Gleichungen in differentieller und integraler Form abgeleitet.

---

, . . . — . . .

     

Thermal behaviour of carbohydrates studied by heat flow calorimetry

The technique of heat flow calorimetry was used to study the thermal behaviour of different carbohydrates between 20°C and 270°C. The samples were analyzed by heating in sealed cells. The temperature range in which exothermic reactions, due to thermal decomposition, occurred varied widely depending on the type of carbohydrate investigated. Reaction enthalpies of 44 sugars and polysaccharides are given. Endothermic phenomena, such as fusion or vaporization of crystallized water, were also observed: fusion temperatures and enthalpies of 34 sugars and sugar alcohols are listed. Calorimetric curves showing crystallization of amorphous sucrose, cellobiose and lactose are also presented.

---

Zusammenfassung Die Technik der Wärmeleitungs-Kalorimetrie wurde zur Untersuchung des thermischen Verhaltens von verschiedenen Kohlenhydraten zwischen 20°C und 270°C eingesetzt. Die Muster wurden in dicht verschlossenen Kapseln erhitzt. Der Temperaturbereich, in welchem exotherme Reaktionen infolge thermischer Zersetzung abliefen, änderte sich stark in Abhängigkeit vom untersuchten Kohlenhydrattyp. Reaktionsenthalpien von 44 Zuckern und Polysacchariden wurden ermittelt. Endotherme Phänomene, wie das Schmelzen oder das Verdampfen von Kristallwasser wurden auch beobachtet. Schmelztemperaturen und Schmelzenthalpien von 34 Zuckern und Zuckeralkoholen sind tabelliert. Kalorimetrische Daten der Kristallisation amorpher Saccharose, Cellobiose und Lactose werden diskutiert.

---

20 270°C. . , . 44 . , . 34 . , , .

---

---

The authors greatly acknowledge many discussions with P. Würsch, R. F. Hurrell and J. Löliger and the technical assistance of F. Michel, Ph. Roulet and S. Reimann.     

ESR studies of coke formation on zeolite catalysts for methanol conversion

Pentasil type zeolite catalysts with different SiO₂/Al₂O₃ ratios carbonized during methanol conversion at 380–420°C have been studied by the ESR method. Factors responsible for the formation of condensed coke structures on their surface have been established. SiO₂/Al₂O₃, 380–420°C. , .     

Influence of the basicity of butyl alcohols on their reactivity

Dehydration of various butyl alcohols in the presence of silicate catalysts with widely ranging strengths of their acidic centers has been studied. Increasing basicity of the reactants or of the strength of acidic centers of catalysts increases the reaction rate. On protonic reaction centers, dehydration proceeds through the equilibrium formation of hydrogen-bonded complexes.

---

, . , . .

     

Kinetics of hydroperoxide reduction by copper(I) O,O-dialkyldithiophosphates

The kinetics of hydroperoxide ROOH (R=H, t–Bu, Ph(CH₃)₂C) reduction by copper(I) O,O-dialkyldithiophosphates has been studied using the UV-spectrophotometric method. Rate constants for the redox reactions have been determined and some suggestions concerning their mechanisms have been made.

---

, - - O,O- (I). .

     

Catalytic properties and radiothermoluminescence of calcium molybdate with MoO3 additives

The addition of excess (1 mol%) MoO₃ to calcium molybdate leads to significant changes in catalytic properties and radiothermoluminescence, thus indicating either the healing of the surface defects of matrices or the formation of solid solutions.

---

MoO₃ I% . . , .

     

Effects of an admixture and fast neutron irradiation on thermal properties of sodium potassium sulphate crystals

The differential thermal analysis curves and the specific heat at constant pressure,C _p, of pure and Cu²⁺-doped sodium potassium sulphate crystals were studied. Different neutron fluences were used up to 2.6×10¹⁰ n/cm², in the temperature range 300–500 K. Impurity incorporation generally increased the specific heat up to a maximum at 5% Cu²⁺ content. The peaks for the doped crystals were shifted to lower temperature as a result of neutron irradiation. This behaviour is discussed on the basis of defects induced by irradiation.

---

Zusammenfassung Es wurden die DTA-Kurven und die spezifische Wärme bei konstantem DruckC _p von reinen, mit Cu²⁺ versetzten Natriumkaliumsulfatkristallen untersucht. Im Temperaturbereich 300–500 K wurden verschiedene Neutronenströme bis zu 2,6×10¹⁰ n/cm² verwendet. Der Einbau von Verunreinigungen erhöht im allgemeinen die spezifische Wärme bis zu einem Maximum bei einem Cu²⁺ Gehalt von 5%. Im Ergebnis der Neutronenbestrahlung verschieben sich die Peaks für die versetzten Kristalle in Richtung niedrigerer Temperaturen. Dieses Verhalten wird auf der Basis strahlungsinduzierter Defekte besprochen.

---

_p . 300–500 2,6 · 10¹⁰ n/². 5%. , . , .

---

---

It is a great pleasure for us to express our deepest gratitude to Prof. Dr. Younis S. Selim for his guidance throughout this work and for providing the irradiation facilities.     

On Ritchie's equation for adsorption kinetics of gases on solids

Ritchie's equation for the kinetic adsorption isotherm has been derived on the basis of the theory describing the kinetics of adsorption of gases on energetically heterogeneous solid surfaces. This eqation has also been generalized to the kinetics of adsorption of multicomponent gas mixtures.

---

. .

     

High-resolution1H NMR and IR spectra of OH-groups of oxide catalysts

Chemical shifts in high-resolution PMR spectra of hydroxyl groups of SiO₂, Al₂O₃, aluminosilicate, phosphate and H-ZSM-5 zeolite catalysts have been measured and compared with IR spectroscopic data and proton charges calculated by the MINDO/3 method.

---

SiO₂, Al₂O₃, , H-ZSM-5. - , MINDO/3.