Catalytic properties of nickel-cobalt mixed oxides and the influence of ionizing radiation

The catalytic and some physico-chemical properties of NiO-Co3O4 and NiO-CoO catalysts have been tested before and after irradiation. Using the decomposition of hydrogen peroxide as a test reaction on storage of the NiO-Co3O4 system, changes in the oxidative abilities as well as in the specific catalytic activities were observed and found to be qualitatively similar. Both these quantities depend non-monotonically on the composition of the NiO-Co3O4 catalysts and they seemed to be notably affected by ionizing radiation. The stationary specific catalytic activity of the NiO-CoO system depended linearly on its surface oxidation ability; this system seems to be insensitive to irradiation and showed a higher general stability. The possible character of the catalytic sites in these catalysts are discussed. (author)