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.

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.

     

Triplet state formation and type II decomposition in the photochemistry of pentanone-2

The concentration dependences of the quantum yields of Norrish type II decomposition from the singlet and triplet states and of the triplet yiel were determined in pentanone-2 photolysis in iso-octane. The results were interpreted by postulating dissociative intersystem crossing of a singlet exciplex as an additional route for the population of the molecular triplet state.

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II -2 . , .

     

Synthesis and properties of hydrodesulfurization catalysts, III. Support effect on the catalytic activity of Co?Mo?Al2O3 catalysts

By means of DTA, reflectanc spectra and measurement of catalytic activity in thiophene hydrogenolysis, the effect of support (aluminium hydroxide and oxide) as well as of the order of introduction of molybdenum and cobalt compounds on the structure and catalytic surface of Co–Mo–Al₂O₃ catalysts is shown.

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, ( ) , Co–Mo–Al₂O₃.

     

Oxidation of ethanol by Ce(IV) in acid nitrate medium

The oxidation kinetics of ethanol by Ce(IV) has been studied as a function of pH, nitrate and water concentration. Even at high concentration of H⁺ and NO ₃ ^– several species appear to exist. The oxidation is fastest in strongly acidic medium without added nitrate ions.

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Ce(IV) pH, . H⁺ NO ₃ ^– , Ce(IV). .

     

Dependence of excitation energy on the coordination of oxygen atoms in cluster models of MgO surface

Cluster models of the MgO surface have been calculated by a semi empirical method. The energies of transitions between the surface states localized on ions of definite coordination are dependent on their coordination numbers. The lower transition energies correspond to a lower coordination number of oxygen ions.

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, . , , , . .

     

Radiolysis of nitrous oxide adsorbed on alumina ionic mechanism of radiolysis of nitrous oxide on alumina with small surface areas

A mechanism is proposed for the radiolysis of adsorbed N₂O describing the experimental dependences of the radiation-chemical yields of O _st ^– and N₂ on N₂O coverages.

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N₂O, - O _st ^– N₂ N₂O.

     

TPD studies of hydrogen adsorption on group VIII metals

Hydrogen desorption proceeds in several temperature regions and differs by its order of magnitude and activation energy. Differential curves of adsorbed hydrogen distribution with respect to the desorption activation energy, dN/dE (E), show a considerable inhomogeneity of adsorbed atomic species and the energetic homogeneity of molecular species.

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. dN/dE (E) .

     

A stochastic analysis of catalyst deactivation in presence of external transfer limitations

The paper analyzes the simplest case of concentration independent deactivation of a catalyst surface in the presence of external transport limitations and accounts for the variations around the mean value of the activity of the catalysts leading to a stochastic formulation. The results reveal interesting features which would not be evident from the conventional deterministic analysis.

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- , , . , .

     

Kinetics of oxidation of adonitol by manganese(III) pyrophosphate

Adonitol is oxidized to ribose by Mn(III) pyrophosphate under the conditions [adonitol] [Mn(III)]. The oxidation rate is first order with respect to both oxidatn and substrate and decreases inversly with [pyrophosphate]_free. Thermodynamic parameters are reported and a suitable mechanism involving free radicals is proposed.

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(III) [] [Mn(III)]. , - []. - .