Thermal behaviour of acidic salts of mixed tetravalent metals

The results of investigations on intercalated crystalline zirconium phosphate are described in the literature. The behaviour of crystalline phosphates containing both zirconium and titanium metal ions has not been investigated previously. Within these investigations, the thermal behaviour of such materials has been studied in the temperature interval 25–1000 °C by simultaneous recording of TG, DTG and DTA curves. The results are presented in this paper.

---

Zusammenfassung Ergebnisse über Untersuchungen an in Schichten eingelagerten kristallinen Zirkoniumphosphat sind in der Literatur beschrieben. Das Verhalten kristalliner Phosphate, die sowohl Zirkoniumals auch Titanmetallionen enthalten, wurde bis jetzt nicht untersucht. Als Teil dieser Untersuchungen wurde das thermische Verhalten solcher Materialien im Temperaturbereich 25–1000 °C durch simultanes Registrieren der TG-, DTG- und DTA-Kurven näher bestimmt, dessen Ergebnisse hier dargelegt werden.

---

. , . , , 25–1000°. .

     

The use of temperature to simplify formose sugar composition

Form ose reaction, the Ca(OH)₂ catalyzed condensation of HCHO to a complex mixture of sugars, does not lose its autocatalytic nature at 98°C. The induction period is 15 sec, and then, at 18% total HCHO conversion, there was a period of approximately 3 sec duration in which the reaction had produced C₆ sugars at 84.3 wt.% selectivity. Glucose amounted to 90% of those sugars, and no branched sugars were detected. Conversion was complete within 3 min. The simple nature of the product was lost at lower temperatures or higher conversions.

---

— HCHO, Ca(OH)₂, 98°C. 15 , 38%- HCHO 3 , C₆ 84,3 . %. 90%, . 3- . .

     

Catalytic incineration of n-hexane on Pt/Al2O3

The catalytic incineration of n-hexane over a Pt/Al₂O₃ catalyst has been studied using a fixed bed reaction. The reaction was carried out in dry air between 250 and 350 °C and at 1 atm pressure. The concentration of n-hexane was between 25 and 300 ppm. The reaction was found to be zero order in n-hexane concentration and the activation energy was found to be 21 kcal/mol. The zero order kinetics can be explained by a surface redox cycle known as Mars-van Krevelen mechanism in which the oxidation of surface Pt is the rate-controlling step.

---

- Pt/Al₂O₃ . , 250–350°C 1 . - 25–300 .. - –21 /. , — , , , Pt.

     

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 .

     

Formation and creeping of the crystalline phase wavefront within the bed of vanadium sulfuric acid catalyst

Kinetics of the reduction of sulfur dioxide by methane in the presence of molecular oxygen at 732–831°C have been obtained.

---

732–831°C.

     

A method to study reaction kinetics over finely-dispersed catalysts in stationary and non-stationary conditions

The application of a small-volume gradientless flow reactor with a vibrofluidized catalyst bed, mass-spectrometric analysis of the reaction products and a membrane turbulizer for alternate purging of the reactor filters by the reaction mixture permits to study the kinetics of complex catalytic reactions over catalysts with 50–100m grains in both stationary and nonstationary conditions.

---

, - 50–100 .

     

Applied chemical thermodynamics and kinetics on pharmaceutical compounds

The important role of thermoanalytical methods in the field of pharmaceutical and galenic research is outlined. The thermodynamic stability of polymorphic forms of a substance is discussed.

---

Zusammenfassung Es wird die wichtige Rolle thermoanalytischer Methoden auf dem Gebiet der pharmazeutischen und galenischen Forschung betont und die thermodynamische Stabilität polymorpher Formen von Substanzen besprochen.

---

. .

     

Investigation of the acid distribution near the reactant-product interface during the thermal decomposition of copper hypophosphite thin layers

During the decomposition of thin layers of copper hypophosphite on a plate, an increased concentration of the active product of the reaction (acid) may be observed near the reactantproduct interface, The acid profile near the interface widens on increase of the decomposition temperature. The profile can also be widened by reducing the efficiency of acid removal to the plate by its preliminary acid saturation. In both cases the rate of interface propagation is increased. The increased reactivity of copper hypophosphite near the interface, and the technological character of the decomposition reaction, are caused by acid diffusion from the reaction product into non-reacted parts of the substance.

---

Zusammenfassung Während der Zersetzung dünner Schichten Kupferhypophosphit kann in der Umgebung der Reaktand-Reaktionsprodukt Grenzfläche eine erhöhte Konzentration des aktiven Produktes der Reaktion (Säure) beobachtet werden. Die Säurezone in der Umgebung der Grenzfläche wird mit zunehmender Temperatur breiter. Diese Zone kann auch durch Verringern der Wirksamkeit der Säureentfernung in Richtung Träger durch dessen vorangehende Säuresättigung verbreitert werden. In beiden Fallen ist die Geschwindigkeit des Grenzflächenzuwachses erhöht. Die erhöhte Reaktivität von Kupferhypophosphit in der Umgebung der Grenzfläche sowie der technologische Charakter der Zersetzurrgsreaktion wird durch Säurediffusion von den Reaktionsprodukten in noch unreagierte Zonen der Substanzen verursacht.

---

— , . . , . . .

     

Hydrogen and oxygen effect on homoexchange rate of ethylene over highly dispersed silver catalysts

Promoting effects of hydrogen and oxygen on the homoexchange rate of ethylene over highly dispersed silver catalysts has been established. On bulk silver no homoexchange is observed under the same conditions.

---

. .

     

Quantum chemical studies of ethylene addition to organoaluminium compounds

In terms of the MINDO/3 method, the surface potential energy of ethylene addition to AlH₃ and Al(CH₃)₃ has been calculated.

---

MINDO/3 AlH₃ Al(CH₃)₃.

     

Dispersion of rhodium on rutile: Comparison of samples prepared by ion exchange and impregnation

Rh/TiO₂ (rutile) samples have been prepared by impregnation (series I) and ion exchange (series C). Upon reduction at low temperature (473 K) the metal dispersity is larger for samples C than for samples I. Removal of surface OH groups in series C cancels the strong Metal-Support Interaction, thus increasing the metal dispersity measured upon reduction at 773 K.

---

Rh/TiO₂ () ( Ї) ( ). (473 K) , . - SMSI- 773 K.

     

Quantum-chemical calculation on models of hydroxy-containing zeolite fragments

Fragments of the zeolite structure have been calculated by the EHT method. The results are in agreement with spectral data on structural hydroxy groups of zeolites.

---

PMX . .

     

Studies of the chemical exchange kinetics of glycinate ions in mixed ligand complexes of copper (II) and glycylglycine

Nuclear magnetic resonance studies of the chemical exchange kinetics of glycinate ions in binary and ternary complexes of copper(II) and glycylglycine indicate the increase in the exchange rate of glycinate ions in the ternary complex. This phenomenon is assumed to be due to the glycinate ion coordination in the axial—equatorial position.

---

(II) . . , - - .

     

Kinetics and mechanism of the oxidation of benzyl alcohol by potassium chlorochromate

The kinetics of the oxidation of benzyl alcohol by potassium chlorochromate, KCrClO₃, has been studied in dimethyl sulfoxide-dichloromethane medium. The reaction is catalyzed by acid. The effects of temperature and solvent composition were studied and activation parameters evaluated. Probable mechanisms are discussed.

---

, KCrClO₃, . . . .

     

CO hydration over catalysts prepared via supporting Fe3(CO)12 and (NEt4)2[Fe2Mn(CO)12] on oxide supports

A comparison of the properties of iron-containing catalysts prepared through carbonyl clusters Fe₃(CO)₁₂ and (NEt₄)₂[Fe₂Mn(CO)₁₂] and iron and manganese nitrates in CO hydration indicates that the addition of Mn incorporated in (NEt₄)₂[Fe₂Mn(CO)₁₂] decreases the methane yield and increases the portion of higher hydrocarbons.

---

, Fe(CO)₁₂ (NEt₄)₂[Fe₂Mn(CO)₁₂] , CO. Mn (NEt₄)₂[Fe₂Mn(CO)₁₂] .

     

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.

---

, , 100–135°C, .

     

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). , , .

     

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.

---

2- 3-. , - , .

     

Zeolite content determination in kaolinic clays via thermal effects

For application in catalysis and adsorption processes, zeolites are synthesized on the surface of spray-dried kaolin microspheres. Various thermal effects are used for the rapid characterization of the zeolite type and content. From DTA measurements, the exothermic lattice break-down peak gives information on the zeolite type and the thermal stability of the sample. Measurements of the heats of immersion by a very simple and quick method allow conclusions about the type and the sorption properties of the zeolite part of the clay. The most precise method to estimate the zeolite content was a standardized technique of desorption and readsorption of water or organic compounds by means of a thermobalance.

---

Zusammenfassung Zur Anwendung in der Katalyse und bei Adsorptinsprozessen werden Zeolithe auf der Oberfläche sprüh-getrockneter Kaolin-Mikrokugeln eingesetzt. Verschiedene thermische Effekte werden zur schnellen Charakterisierung des Zeolith-Typs und -Gehalts genutzt. Der exotherme DTA-peak beim Gitterzusammenbruch liefert Informationen über Zeolith-Typ und thermische Stabilität der Probe. Eine sehr einfache Schnellmethode zur Messung der Immersionswärmen erlaubt Schlussfolgerungen über Typ und Sorptionseigenschaften des zeolithischen Anteils des Tons. Die genaueste Methode zur Bewertung des Zeolithgehalts war eine standardisierte thermogravimetrische Desorptions- und Readsorptions-Methode mit Wasser oder organiscen Verbindungen.

---

, , , . . , . , , . , .

     

Modifying action of carbon dioxide in catalytic oxidation of ethylene on silver

Carbon dioxide exerts a strong inhibitory effect on oxygen adsorption and complete oxidation of ethylene on silver but has little effect on the rate of ethylene oxidation to ethylene oxide.

---

.