Oxidative Dehydrogenation of 1‐Butene Over Magnetite

Magnetite (FC 3 O 4 ), a partially reduced iron oxide, has long been considered as inactive in the oxidative dehydrogenation of butene. By studying a clean Fe 3 O 4 powder, we found that Fe 3 O 4 , similar to other spinel ferrites, is not only active, but also more active and selective than α‐Fe 2 O 3 . The active site densities and the desorption temperatures of oxidation products on Fe 3 O 4 were also measured. Fe 3 O 4 is, however, unstable under flow reaction conditions. Even if the bulk of the oxide is stabilized in the form of Fe 3 O 4 at high temperatures and low O 2 /C 4 ratios, its surface is gradually oxidized to a form close to α‐Fe 2 O 3 , resulting in a decrease in both the activity and selectivity. The restructuring of the FC 3 O 4 surface is temperature dependent. At 300°C, the high selectivity and activity of a low‐surface‐area Fe 3 O 4 can be long preserved even if the bulk is oxidized to α‐Fe 2 O 3 .