The catalytic properties of unsupported cobalt and nickel oxide catalysts toward ethane and ethylene oxidation were compared, and the results indicated that more ethylene as intermediate product can be subsequently oxidized into degradation products, CO_x, over the former than over the latter. As increasing and/or decreasing reaction temperature, the catalytic behavior of CoO/SiO₂ prepared recently indicated that the aging of catalyst is very sensitive to the pretreatment condition. In-situ Weiss magnetism measurement result over supported cobalt oxide showed that the cobalt still remains as Co²⁺ even if the oxygen in feed has been consumed. It indicated that the cobalt reduction is difficult due to the interaction between active phase and support. That the catalytic activity is related to the ease of the Co³⁺Co²⁺ transition, and a hetero-homogeneous mechanism reflected in ODHE reaction over cobalt-based catalysts was suggested.

Key words: cobalt oxide, ethane, oxidative dehydrogenation, ethylene, mechanism, metal oxide-support interaction