Monolayer vanadia on titania systems from alkoxide precursors. Part III. Activity in secondary alcohol oxidation

The activity of V⁵⁺ ion monolayer supported on anatase, rutile, and anatase-rutile mixed carrier and of bulk V₂O₅ was examined in isopropyl alcohol and cyclohexanol oxidation. Catalysts exhibited remarkable activity in ketone formation. At higher temperatures benzene was the predominant product of cyclohexanol reaction.

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V⁵⁺, , - V₂O₅, . . .

     

Kinetics of isotopic exchange due to one elementary reaction

Kinetic equations of the isotopic exchange in a system with one elementary reaction have been derived. A principle of quasistationarity in the isotopic kinetics has been formulated.

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. .

     

Catalytic and acidic properties of different metal-zeolite catalysts

Catalytic and acidic properties of bifunctional catalysts containing faujasite, superhigh-silica zeolite and mordenite have been studied in isomerization of C₈-alkylaromatic hydrocarbons.

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C₈ , , - .

     

Properties of highly dispersed supported catalysts in hydrogenation reactions

Pt/sol and Pt/support catalysts with 6–15 Å Pt particles have been established to be low active in the hydrogenation of propargyl alcohol, butyn-l-ol-3 and dimethylethynylcarbinol. The specific catalytic activity significantly rises with increasing d_Pt above 15 Å and after the thermal treatment of highly dispersed catalysts in a hydrogen flow.

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, -30 -- 6–15 Å , -1, -3 . d_Pt>15 Å .

     

Kinetics of heterogeneous catalytic hydroformylation of propylene on rhodium-cobalt catalysts. Reaction mechanism

Steady-state kinetics of combined heterogeneous catalytic hydrogenation and hydroformylation of propylene on Rh–Co-containing catalysts has been studied at atmospheric pressure and T=140–170 °C. A reaction mechanism is suggested. The kinetic model adequately describes all observations.

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- Rh–Co- 140–170 °C. . , .

     

Thermal and thermoxidative decomposition of ternary grafted copolymers of ABS type

The thermal (under high vacuum, 10^–5 mm Hg) and thermoxidative decompositions of ternary grafted copolymers of ABS type were studied, the dependence of the characteristic thermal data on the overall composition being followed over narrow ranges of variation of comonomer content.It was found that the nature of the solid products obtained on thermal decomposition is dependent on the copolymer structure.

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Zusammenfassung Die thermischen (unter Hochvakuum, 10^–5 mm Hg) und thermooxidativen Zersetzungen ternärer Kopolymere der Typen ABS wurden untersucht, wobei die Abhängigkeit der charakteristischen thermischen Daten von der allgemeinen Zusammensetzung über enge Bereiche der Änderung des Komonomergehaltes verfolgt wurde. Es zeigte sich, daß die Beschaffenheit der bei der thermischen Zersetzung erhaltenen festen Produkte von der Kopolymerstruktur abhängig ist.

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( 10^–5 Hg) ABC. , . , , , .

     

Pt?Fe2O3 catalytic system for hydrogenation reactions

The effect of Fe₂O₃ additives on crotonaldehyde hydrogenation over group VIII metals has been studied. Iron oxide added to platinum black exerts a modifying effect on the reduction of the carbonyl group of croton-aldehyde inhibiting hydrogenation of the C=C bond conjugated with a C=O group.

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Fe₂O₃ VIII -. , , - , C=C , C=O-.

     

Vapor-phase oxidation of 2,6-dimethylpyridine on vanadium-molybdenum catalysts

The catalytic activity of vanadium-molybdenum catalysts in oxidation of 2,6-dimethylpyridine is compared with their adsorption properties and phase composition. The increase of molybdenum content results in the decrease of irreversible adsorption and total conversion of 2,6-dimethylpyridine. The reversible adsorption depends on the phase composition and character of crystalline modifications of MoO₃ in the catalysts.

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2,6- . 2,6-. MoO₃ .

     

Kinetic regularities for the interaction of anion-radicals O2? with benzene and toluene on Mo?Mg oxide systems

Interaction of anion-radicals O ₂ ^– with adsorbed forms of benzene and toluene at 293–473 K is shown to be described by an equation corresponding to exponential activation energy distribution of O ₂ ^– . It has been established that under the same conditions the decay rate of O ₂ ^– is higher in the presence of toluene than with benzene.

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, - O ₂ ^– 293–473 , O ₂ ^– . , O ₂ ^– , .

     

Identification of exchange-coupled V4+ and Cu2+ ions in Cu?V?Mo oxide systems

ESR studies of X(CuO)·V₂O₅·8.3 MoO₃ (X=1–2) calcined in flowing nitrogen at 250–350 °C have revealed the exchange interaction of Cu²⁺ and V⁴⁺ ions that form a paramagnetic system.

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X(CuO) V₂O₅·8,3 MoO₃, X=1–2, , 250–350°C, Cu²⁺ V⁴⁺, .