Catalytic properties of phosphorus-containing rhenium complexes in the hydrogenation of hexene-1

Rhenium (V, VI) complexes with organophosphorus ligands proved to be catalytically active in hexene-1 hydrogenation. The kinetics of this process catalyzed by ReOCl₃(PPh₃)₂ has been examined. The organic ligand in the coordination sphere of rhenium complexes was found to affect selectivity to olefin bonds or nitro groups in the hydrogenation of hydrocarbons.

---

(V, VI) -1. , ReOCl₃ (PPh₃)₂. , .

     

Vibrational excitation effects on silane reactivity in its reaction with bromine atoms

A rate increase of SiH₃Br formation in SiH₄ photobromination under irradiation by a cw CO₂ laser is reported. At low SiH₄ pressures (1–2 Pa) the radiation effect is shown to be isotope-selective.

---

SiH₃Br CO₂ SiH₄. , SiH₄ (1–2 ) .

     

Pt(alizarine)2 complex adsorbed on titanium dioxide as a sensitizer in photocatalytic evolution of dihydrogen

Pt(alizarine)₂ complex adsorbed on the surface of titanium dioxide has been found to cause spectral sensitization of the photocatalytic activity of TiO₂. Adsorption of the complex provides simultaneously sensitization of the photoprocess and catalysis of dark steps of dihydrogen formation.

---

, Pt()₂ TiO₂. , , .

     

The effect of preparation conditions on the activity and stability of copreciptitated Ni/Al2O3 catalysts for the methanation of carbon monoxide

The activities and stabilities of coprecipitated Ni/Al₂O₃ methanation catalysts depend markedly on their preparation and pretreatment. The results are discussed in relation to the structure of the precipitate and to changes which occur during calcination and reduction.

---

Ni/Al₂O₃ . , .

     

The question of thermal decomposition of pyrite

The thermal decomposition of monomineral pyrite was studied in an inert atmostphere. From an analysis of the values of the thermal effects, an interpretation of the hree physicochemical processes recorded in the thermoanalytical curves is proposed.

---

Zusammenfassung Die thermische Zersetzung von monomineralem Pyrit wurde in inerter Atmosphäre untersucht. An Hand der Analyse der Werte der thermischen Effekte wird eine Beschreibung dreier, in den thermoanalytischen Kurven festgehaltener physikalischchemischer Vorgänge vorgeschlagen.

---

Résumé On a étudié la décomposition thermique de la pyrite, en atmosphère inerte. On propose une interprétation des trois processus physicochimiques enregistrés sur les courbes thermoanalytiques, qui repose sur l'analyse des effects thermiques.

---

- , .

     

Electrocatalytic effect of metal ions on lead and lead dioxide electrode reactions

The electrochemical reactions which take place on lead and lead dioxide electrodes of a lead-acid battery are highly influenced by the presence in the electrolytic solution of ions Cd(II), Ni(II), Zn(II) and Co(II). Current density-potential curves were obtained in this work by using a Pb/Ca alloy. It was observed that Co(II) and Ni(II) ions catalyzed both hydrogen and oxygen evolution reactions. On the other hand, Cd(II) and Zn(II) ions decreased the hydrogen evolution rate.

---

, - , Cd(II), Ni(II), Zn(II) Co(II). - , Pb/Ca. , Co(II) Ni(II) , . , Cd(II) Zn(II) .

     

Hydrogenation of ethylene on gadolinium X, Y and L-type zeolites

It is shown that Gd-zeolites have a catalytic activity towards ethylene hydrogenation at 1 atm. This activity decreases with an increase in the SiO₂/Al₂O₃ ratio from 2.2 to 6.1 and 4.1, i.e. upon going from an X type zeolite to Y and L. For these types of zeolite the activity grows with an increase in Gd³⁺ content from 50 to 80%. Oxygen addition to the reaction mixture stabilizes the catalytic activity of zeolites.

---

, qv 1 . , SiO₂/Al₂O₃ 2,2 6,1 4,1, .. X Y L. , 50 80%. .

     

Studies of V?Mo?O systems with small vanadium content in acrolein oxidation

A solid solution of vanadium in MoO₃ with a solubility limit of about 3 mol.% V₂O₅ is shown to be formed. Its catalytic properties are discussed.

---

MoO₃ 3 . % V₂O₅ .

     

Effect of the reduction of Sn?Sb oxide catalyst on its activity

The decreased total activity and increased selectivity of an Sn–Sb catalyst in isobutylene partial oxidation are due to its decreasing activity in deep oxidation caused by surface reduction and the blocking of its centers responsible for deep oxidation.

---

, - , , , , .

     

Fischer-tropsch synthesis over ruthenium/Y-zeolite catalysts: Effects of the neutralizing cations of zeolites

The effect of steaming on HZSM 5 has been characterized by using two model reactions: n-heptane cracking and m-xylene isomerization. For both reactions, the activity of HZSM 5 was increased by steaming at low water vapor pressure, but at a high pressure it became lower than that of the non-steamed sample. Modifications in the acidity and a slight blockage of the pores by extralattice aluminium can explain this behavior.

---

HZSM 5 : - -. HZSM 5 , , . .

     

An investigation on the effects of additives during the thermochemical decomposition of phosphogypsum under isothermal conditions

A study was made of the isothermal kinetics of phosphogypsum in the presence of additives and in a reducing gaseous medium.

---

Zusammenfassung Es wurden isotherme kinetische Untersuchungen an Phosphogips in Gegenwart von Zusätzen sowie m reduzierender Atmosphäre durchgeführt.

---

- .

     

Reasons for different activities of various type catalysts in reactions of oxidation of inorganic substances

The dual role of catalysts in the interaction between an inorganic molecule AB and adsorbed oxygen ZO, as an electron donor (in the oxidative addition of AB) and as an electron acceptor (in subsequent ZO reduction), permits to interpret the orders of activities of various optimal catalysts and their dependence on the AB structure.

---

AB ZO — ( AB) ( ZO). AB.

     

Catalytic properties of palladium oxide systems in the hydrogenation of crotonaldehyde

Catalytic properties of Pd black-oxide systems have been studied in hydrogenation of crotonaldehyde. It has been revealed that the additions of basic and amphoteric oxides (MgO, Fe₂O₃ and ZnO) increase the hydrogenation rate of the ethylenic bond in crotonaldehyde.

---

Pd-- . , (MgO, Fe₂O₃, ZnO) .

     

Kinetics of oxidative sulfonation of butylamine in the presence of CuCl2

Kinetic regularities of butylamine sulfonation to N, N-dibutylsulfamide in the presence of copper(II) chloride have been studied. Reaction mechanism involves the formation of Cu(II) amine complexes, their subsequent interaction with SO₂ and the redox decomposition of an intermediate to final products.

---

N-N- (II). Cu(II), SO₂ - .

     

Thermal analysis of phenolic resin based pyropolymers

The formation and thermal behaviour of pyropolymers based on novolak resin synthesized under carefully controlled processing conditions have been studied by various thermoanalytical techniques. A suitable reaction scheme has been proposed for the formation of these pyropolymers. Only a small (3–8%) weight loss has been observed up to 800 °C in static air. DTA curves confirmed multistage exothermic processes predominantly due to two different linkages which control their thermo/thermo-oxidative stability. Hot metal filtration (700 °C) in an inert atmosphere exhibited only negligible weight loss.

---

Zusammenfassung Mittels verschiedener thermoanalytischer Verfahren wurde Bildung und thermisches Verhalten von Pyropolymeren auf Novolackbasis unter streng geregelten Reaktionsbedingungen untersucht. Zur Bildung dieser Pyropolymere wurde ein geeignetes Reaktionsschema entwickelt. In unbewegter Luftatmosphäre kann bis 800 °C nur ein geringer (3–8%) Gewichtsverluft beobachtet werden. Die DTA-Kurven zeigen einen exothermen Mehrstufenprozeß, der hauptsächlich auf zwei verschiedene Verkettungen zurückzuführen ist, welche die thermische/thermisch-oxidative Stabilität bestimmen.

---

. . 800° (3–8%) . , , / - . (700° .

     

ESR study of free radicals chemically generated at high pressure

Free radicals generated by the thermal decomposition of benzoyl peroxide in polyacrylnitrile were studied by the ESR method at 700 MPa between 100 and 130°C. The formation and decay of macroradicals were investigated and the mechanism of macroradical generation is discussed.

---

700 MPa 100 130°C. .