ACTIVITY OF TRANSITION METAL OXIDES FOR CYCLOHEXANE DEHYDROGENATION

The dehydrogenation of cyclohexane has been studied in a flow reactor on a number of oxide catalysts. Rate constants and apparent activation energies were determined in the temperature range 400-465 °C, and it was shown that the reaction is essentially first order with respect to cyclohexane pressure. Comparison of the rate constants at 450 °C for the oxides studied indicates that the catalytic activity is determined by the 3d electron configuration of the metal ion. Highest activity was associated with the d3, d2, and d1 configurations, while low activity was associated with the more stable d0, d5, and d10 configurations. The results support previous studies of hydrogen and hydrocarbon reactions at oxide surfaces and can be discussed in terms of the application of crystal field theory to the formation of surface complexes. © 1969.