1971 Volume 44 Issue 10 Pages 2595-2600
The oxidative dehydrogenation of cyclohexane over molecular sieves ion-exchanged with cupric ion (Cu(II)–Y) was investigated by means of an ordinary flow reactor with a reactant gas composed of 1.0% cyclohexane, 50% oxygen, and 49% nitrogen. The reaction was studied at temperatures between 210–350°C; here, carbon dioxide and benzene were the main products. The Cu(II)–Y was found to be a very active catalyst for the oxidation of cyclohexane as well as for that of olefins, in comparison with an ordinary cupric oxide catalyst supported on silica gel; the selectivity for benzene formation was as high as 80% below 10% conversion. Both products were found to be formed in competitive reactions. The catalytic activities were also studied on molecular sieves ion-exchanged with other transition metal ions, such as palladium (II), silver (I), and zinc (II). The relations between the catalytic activities and the heats of formation of the corresponding metal oxides per g-atom oxygen were examined; volcano-shaped correlations were observed for both benzene and carbon-dioxide formations for these catalysts. The most active catalyst was Cu(II)–Y for benzene formation, whereas it was Pd (II)–Y for the carbon dioxide formation. The meaning of the correlations was discussed according to Balandin’s explanation, based on thermochemistry, although no satisfying explanation was found. The compensation effects were observed between the activation energies and the frequency factors in these oxidations.
This article cannot obtain the latest cited-by information.