Catalytic activity of palladium-containing zeolites in the complete oxidation of benzene

The dependence of palladium distribution in zeolites on the temperature of thermal treatment has been established from the data on oxygen chemisorption and the statistical processing of electron micrographs. The influence of palladium distribution in zeolites on their catalytic activity towards the complete oxidation of benzene has been shown.

---

- . .

     

Adsorption properties of microporous silica

The study of CCl₄ adsorption shows that the increase of dispersion potential can increase the specific adsorption in pores up to 3 nm in size.

---

CCl₄ , 3 .

     

Photochemical reactions of anthraquinone with hydrocarbons in the presence and absence of oxygen: Trapping of radical intermediates

Radical intermediates formed at 25°C in the presence and absence of oxygen during the photolysis of anthraquinone in aromatic, cyclic and aliphatic hydrocarbon solvents were trapped by 2,6-dichloronitrosobenzene, 2,6-dibromonitrosobenzene and 2,4,6-tribromonitrosobenzene. The resulting nitroxide radicals have been characterized in situ by ESR spectra.

---

: 2,6-, 2,6- 2,4,6-— , , 25°C. .

     

Kinetics and mechanism of OsO4 catalyzed oxidation of chalcones by Ce4 in aqueous acetic sulfuric acid media

Kinetics of OsO₄ catalyzed oxidation of chalcones by Ce⁴⁺ has been studied in aqueous acetic-sulfuric acid medium in the temperature range 313 to 338 K. The order in [oxidant] is zero while the order with respect to [substrate] and [catalyst] are each fractional. The rate of the reaction decreased with increase in percentage of acetic acid while [H⁺] had practically no effect on the rate The rates of various substituted chalcones (with substituents in the phenyl. ring attached to the moiety) are in the orderp-CH₃>m-CH₃>H>p-Cl>m-Cl>m-NO₂>p-NO₂. A mechanism in which formation of a cyclic ester between chalcone and OsO₄ in a fast step followed by its decomposition in a rate-determining step is envisaged.

---

Ce⁴⁺, OsO₄, - 313–338 . —, —. , [H⁺] . ( , : -CH₃>-CH₃>H>-Cl>-NO₂>-NO₂. , OsO₄ , , .

     

Some investigations on the photostabilization of polypropylene

The effect of substituted hydroxybenzophenone, benzotriazole and organic metal complexes on the photooxidation of PP films has been studied. It has been established that NiDBTC added in 1.0 wt. % is the most effective photostabilizer.While in the case of other stabilizers there is a slight increase in the Co content even during the induction period, with the application of NiDBTC practically no oxidation can be observed before the stabilizer completely disappears. This means that NiDBTC inhibits the photooxidation of the polymer even in low concentration.

---

, - . , Ni, 1,0 . %. . , Ni , . , Ni .

     

Partial oxidation of methane on Cr2O3/Al2O3

The oxidation of methane on supported chromia was studied at temperatures varying between 423 and 743 K and CH₄/O₂ ratios between 1 and 9 in a differential reactor. The main reaction products observed were carbon monoxide and formaldehyde. The rates of reaction obey a power law expression.

---

, 423 743 CH₄/O₂ 1 9, . . .

     

Effect of the support on the coking of nickel catalysts in hydrocarbon steam reforming

Experiments on the coking rates of variously prepared nickel catalysts on TiO₂, Al₂O₃ and MgO in n-butane steam reforming show that changes in the relative coking rate at a rising steam excess in the gas phase depend mainly on the kind of support. The results obtained are accounted for by changes in the electron density at the site of nickel crystallite contact with the surface of various supports.

---

, TiO₂, Al₂O₃ MgO, - , , , , , . .

     

IR study of interaction of propylene at CoO-MgO and CoO-MoO3-MgO surfaces

IR spectra of propylene adsorbed in CoO-MgO and CoO-MgO-MoO₃ solid solutions show that a surface -complex with Co²⁺ ions is formed, strongly bonded in the former case and weakly in the latter. Thus, introduction of Mo strongly modifies the catalytic properties of Co²⁺ active centers. In the presence of oxygen, allylic species, aldehyde and carboxylate complexes appear.

---

, CoO-MgO CoO-MgO-MoO₃ - Co²⁺, . , Mo Co²⁺. - .

     

Activity of Ni?Mo hydrodesulfurization catalysts supported on mixed alumina-zirconia

The hydrodesulfurization (HDS) of thiophene by nickel-molybdenum catalysts supported on alumina-zirconia has been investigated. The effect of varying the ratios of oxides in the support is to produce a minimum in the activity for HDS, and the coimpregnated catalysts are shown to be more active than the analogous co-precipitated catalysts.

---

(HDS) -, . HDS. , .

     

Differential scanning calorimetry study of reactions of phenyl glycidyl ether with phosphoric acid

The reactions of phenyl glycidyl ether (PGE) with phosphoric acid in three molar ratios have been studied by means of DSC alone. The results obtained from isothermal measurements are as follows:H=–91.0 kJ/mole PGE(1:1 molar ratio);H=–100.5 kj/mole PGE (1:2/3 molar ratio).The DSC curves obtained from dynamic experiments are multipeaked and giveHvalues higher than those obtained from isothermal measurements. These results can be explained by taking into account the acid concentration, the different reactivities of the hydrogens of the phosphoric acid and the possibility that secondary reactions occur.

---

Zusammenfassung Die Reaktion von Phenylglycidyläther (PGE) mit Phosphorsäure wurde bei drei verschiedenen molaren Verhältnissen allein mittels DSC untersucht. Isotherme Messungen ergaben folgende Werte:H=–91.0kJ/mol PGE (molares Verhältnis 1:1);H=–100.5 kJ/mol PGE (molares Verhältnis 3:2). Die bei dynamischen Experimenten erhaltenen DSC-Kurven weisen viele Peaks auf und ergebenH-Werte, die größer als die durch isotherme Messungen erhaltenen sind. Diese Ergebnisse können erklärt werden, wenn die Säurekonzentration, die unterschiedliche Reaktivität der Wasserstoffatome der Phosphorsäure und die Möglichkeit des Verlaufs sekundärer Reaktionen in Rechnung gestellt werden.

---

() () . 11 12/3, H, –91.0 –100.5 ·^–1. , , H . , , .