Oxidative dehydrogenation of propane to propylene on spinel type zinc gallate and zinc aluminate catalysts

Abstract

The ZnGa₂O₄ and ZnAl₂O₄ spinels have been synthesized by glycothermal method, characterized with the XRD and BET single point method, and tested in the oxidative dehydrogenation of propane. For the ZnGa₂O₄ spinels, the activity and selectivity to propylene increase with increasing the suitable Ga contents and ZnGa₂O₄ Zn/Ga atomic ratio 0.50 has highest performance at reaction temperatures 525℃-600℃. The Ga ions surrounded by oxygen in the spinel structure are proposed as active center for oxidative dehydrogenation of propane to propylene. The different in catalytic behavior of ZnGa₂O₄ and ZnAl₂O₄ have been ascribed to different coordination of Ga ions and A1 ions in the two groups of the spinels and to the lower oxygen cation’s bond energy in the ZnGa₂O₄ spinels. For ZnAl₂O₄ spinel propylene selectivity is higher than ZnGa₂O₄.