Yoshisato Tezuka

The catalytic activity and electric resistance of evaporated copper-nickel films

Abstract The dependencies of the hydrogenation catalytic activity and electric resistance of copper-nickel films upon the composition of the film were investigated. The film was prepared by the evaporation of copper and nickel metals or their alloys on a substrate cooled by liquid oxygen. Prior to use, the film was treated in a vacuum at 30 ° or 250 °C. The catalytic activity was tested by the hydrogenation reaction of ethylene. The maximum of activity for the reaction was always found in the alloy region of the film, irrespective of the order of the deposition of the two metals, when the film was treated at 30 °C. However, the maximum activity shifted to the pure nickel, when the treatment temperature was raised to 250 °C. The electric resistance of 50% nickel film was always maximum. It was also noted that an increase in treatment temperature resulted in a marked decrease in electric resistance, especially on 50% nickel film. The catalytic activity is discussed in view of the change of the amount of the especially unstable lattice imperfections in the film.

Adsorption Characteristics in Reversed-Phase Liquid Chromatography Using Ethanol/Water Mixed Solvent

Adsorption characteristics were studied in a reversed-phase liquid chromatography consisting of an octadecylsilyl (ODS)-silica gel and ethanol/water mixture (70/30, v/v), and were compared with corresponding results obtained by using methanol/water and acetonitrile/water mixtures (70/30, v/v) as mobile phase. Similar tendencies were observed for some adsorption characteristics in the three chromatographic systems. However, the magnitude of the characteristics was not entirely identical in the three systems. Surface diffusion was dominant for intraparticle diffusion in the ODS-silica gel particles irrespective of the type of the organic modifiers in mobile phases. A few correlations were confirmed with regard to surface diffusion, i.e., an enthalpy-entropy compensation and a linear free-energy relation. The analogous correlations on surface diffusion phenomena suggest the similarity in the mechanism of surface diffusion in the three chromatographic systems.

Radiographical Study of Cu–Ni Catalysts Irradiated with α-Rays

were investigated by means of autoradiography using tritium as a tracer. In the case of alloy sheets, a marked increase upon the irradiation in the amount of adsorbed hydrogen was found at the region carrying the alloy. In the case of the evaporated films, the amount of adsorbed hydrogen in the alloy region decreased upon irradiation, when the film was preliminarily sintered at 30 °C. However, the amount increased, when the film was preliminarily sintered at 250 °C. The change in the activity upon irradiation was formulated as the function of the electronic factor and the structural factor of the alloy.

The catalytic deoxidation reaction of propylene oxide on copper oxide

Abstract The reaction mechanism in the catalytic formation of propylene from propylene oxide on copper oxide was investigated by using various copper oxides and reduced copper. The amount of propylene produced in the initial stage of the reaction on reduced copper was greater than that produced on copper oxide. The addition of oxygen to propylene oxide promoted catalytic formations of both propylene and carbon dioxide. The formation of these products was strongly curtailed by adding potassium iodide to the catalyst. These findings and results reported elsewhere on the exchange of oxygen between propylene oxide and copper oxide suggest that two different mechanisms, the redox cycle mechanism and the peroxide mechanism, proceed in parallel in the stational state of the reaction which produces propylene.