AbstractMagnetite (FC3O4), a partially reduced iron oxide, has long been considered as inactive in the oxidative dehydrogenation of butene. By studying a clean Fe3O4powder, we found that Fe3O4, similar to other spinel ferrites, is not only active, but also more active and selective than α‐Fe2O3. The active site densities and the desorption temperatures of oxidation products on Fe3O4were also measured. Fe3O4is, however, unstable under flow reaction conditions. Even if the bulk of the oxide is stabilized in the form of Fe3O4at high temperatures and low O2/C4ratios, its surface is gradually oxidized to a form close to α‐Fe2O3, resulting in a decrease in both the activity and selectivity. The restructuring of the FC3O4surface is temperature dependent. At 300°C, the high selectivity and activity of a low‐surface‐area Fe3O4can be long preserved even if the bulk is oxidized
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