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Oxidative dehydrogenation (ODH) of ethane over the V 2 O 5 (001) surface has been carried out using periodic density functional theory (DFT) calculations. We show that the first C-H bond activation leading to an ethoxide intermediate is the rate-limiting step of the reaction. The most feasible pathway for the C-H bond activation is predicted to take place at the O(1) (VdO) site, with activation energy of 35.1 kcal/mol. The O(2) (V-O-V) site is less active for C-H bond activation, with an energy barrier of 37.6 kcal/mol. However, the O(1) site exhibits much lower selectivity to ethene formation than O(2) because the side reaction leading to acetaldehyde occurs more easily than ethene production on O(1), whereas O(2) is inert for acetaldehyde formation. On the basis of our results, the ODH reactions of ethane and propane are systematically compared and discussed.

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