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Oxidative dehydrogenation (ODH) of n‐butene with V−Mg complex oxide catalysts was carried out with a fixed‐bed flow reactor at 480 °C. In order to improve the catalytic performance of V−Mg complex oxide, we examined the effect of added metal oxide on the ODH of n‐butene. When Fe was added to the V−Mg complex oxide, the reactivity of lattice oxygen in the V−Mg complex oxide increased. V−Mg‐Fe(20:30:10) prepared at a molar ratio of V:Mg:Fe=20:30:10 showed high conversion (53.9%) and buta‐1,3‐diene (BD) yield (20.3%) in the ODH with the lattice oxygen. To continuously produce BD, ODH under O2 flow was also investigated. The V−Mg‐Fe(20:30:10) catalyst exhibited higher BD yield than the V−Mg catalyst, and it was indicated that the high reactivity of the lattice oxygen affected the ODH under O2 flow. Moreover, the V−Mg‐Fe(20:30:10)‐800 catalyst calcined at 800 °C showed highly stable ODH activity, and the BD yield (11%) was maintained for 420 min. XRD analysis results of the catalyst showed that the maintenance of the ODH activity could be attributed to the maintenance of the crystalline structure of V−Mg‐Fe(20:30:10)‐800 during the reaction.

Oxidative dehydrogenation (ODH) reactions of but-1-ene with copper and iron oxide catalysts were carried out with a fixedbed flow reactor in a temperature range of 230-350 8C at 1-C 4 H 8 (mL/min)/O 2 (mL/min) flow ratios of 5/1, 5/2.5, 5/4, and 5/5 for 100 min. When CuFe 2 O 4 /AC prepared in the presence of activated carbon at a molar ratio of Cu/Fe = 1/2 was used for the ODH under reaction conditions of 270 8C and 1-C 4 H 8 /O 2 = 5/ 5, the highest BD (buta-1,3-diene) yield of 15% for 100 min was achieved. When the usability of the CuFe 2 O 4 structure was evaluated, it was clarified that the ODH and complete oxidation proceeded on copper oxides. In addition, CuFe 2 O 4 /AC mainly advanced the ODH, while CuO and Cu 2 O promoted the complete oxidation. CuFe 2 O 4 /AC catalyst showed the good catalytic performance in the ODH of but-1-ene at a low temperature of 270 8C. According to XRD and XPS analyses of CuFe 2 O 4 /AC, CuO/AC, and Cu 2 O before and after the reaction, most of the crystalline CuO phase changed to the Cu 2 O phase during the ODH, and the Cu 2 O phase was maintained in the ODH. These results indicated that complete oxidation occurred with the Cu 2 O phase. In the case of CuFe 2 O 4 /AC, although Cu species in CuFe 2 O 4 were also reduced to Cu 2 O, many CuFe 2 O 4 structures and Cu 2 + species were maintained. This suggested that the maintenance of the CuFe 2 O 4 structure and Cu 2 + species is important in the production of BD.[a] T.