The mechanism of catalytic action on oxidative dehydrogenation of ethane over NiO has been investigated by means of O~2-TPD, pulse measure, in situ Weiss magnetic methods and TAP (temporal analysis of products) experiments. It is found that the oxidized Ni is maintained in the course of ODHE reaction. The exchange between gas phase oxygen and nonstoichiometric oxygen (α, β oxygen species) is reversible, and the β oxygen species (possibly O^-), which exists both on the surface and in the bulk of the catalyst, shows higher selectivity towards ethylene than the α one (possibly O~2^-, O~2^2^-) which just exists on the surface of the catalyst. The mechanism is proposed that the ethylene, which is not only the product but also the intermedium of forming CO~2, forms from the reaction of the O^- with ethane on the catalysts' surface, and the CO~2 forms by the reaction of ethylene and/or C~2H~5 with O~2^-, O~2^2^- and O~2~(~s~). The catalyst is reoxidized with the help of the reaction between oxygen vacancy, lattice oxygen and oxygen adsorpted.

Key words: NICKEL OXIDE, ETHANE, OXO-DEHYDROGENATION, ETHYLENE, CATALYTIC MECHANISM, CATALYST