Lanthanoid-free perovskite oxide catalyst for dehydrogenation of ethylbenzene working with redox mechanism

For the development of highly active and robust catalysts for dehydrogenation of ethylbenzene (EBDH) to produce styrene; an important monomer for polystyrene production, perovskite-type oxides were applied to the reaction. Controlling the mobility of lattice oxygen by changing the structure of Ba(1 − x)Sr(x)Fe(y)Mn(1 − y)O(3 − δ) (0 ≤ x ≤ 1, 0.2 ≤ y ≤ 0.8), perovskite catalyst showed higher activity and stability on EBDH. The optimized Ba/Sr and Fe/Mn molar ratios were 0.4/0.6 and 0.6/0.4, respectively. Comparison of the dehydrogenation activity of Ba(0.4)Sr(0.6)Fe(0.6)Mn(0.4)O(3 − δ) catalyst with that of an industrial potassium promoted iron (Fe–K) catalyst revealed that the Ba(0.4)Sr(0.6)Fe(0.6)Mn(0.4)O(3 − δ) catalyst showed higher initial activity than the industrial Fe–K oxide catalyst. Additionally, the Ba(0.4)Sr(0.6)Fe(0.6)Mn(0.4)O(3 − δ) catalyst showed high activity and stability under severe conditions, even at temperatures as low as 783 K, or at the low steam/EB ratio of 2, while, the Fe–K catalyst showed low activity in such conditions. Comparing reduction profiles of the Ba(0.4)Sr(0.6)Fe(0.6)Mn(0.4)O(3 − δ) and the Fe–K catalysts in a H(2)O/H(2) atmosphere, reduction was suppressed by the presence of H(2)O over the Ba(0.4)Sr(0.6)Fe(0.6)Mn(0.4)O(3 − δ) catalyst while the Fe–K catalyst was reduced. In other words, Ba(0.4)Sr(0.6)Fe(0.6)Mn(0.4)O(3 − δ) catalyst had higher potential for activating the steam than the Fe–K catalyst. The lattice oxygen in perovskite-structure was consumed by H(2), subsequently the consumed lattice oxygen was regenerated by H(2)O. So the catalytic performance of Ba(0.4)Sr(0.6)Fe(0.6)Mn(0.4)O(3 − δ) was superior to that of Fe–K catalyst thanks to the high redox property of the Ba(0.4)Sr(0.6)Fe(0.6)Mn(0.4)O(3 − δ) perovskite oxide.