The Effect of Oxygen Binding Energy on the Selective Oxidation of Butane Over V/γ-AL₂O₃

The oxidation of butane was studied over two V/γ-Al₂O₃ catalysts with loadings of 2.9 and 8.2 V/nm² using both pulse reaction and steady state measurements. The activity per V ion was about ten times higher on the higher loading sample. In the pulse reaction, the selectivity for oxidative dehydrogenation increased with increasing extent of reduction of the vanadia phase, ϕ, on both catalysts. Small amounts of oxygenates were observed on the lower loading sample. The change in selectivity with ϕ correlated well with changes in the heat of reoxidation of the reduced catalysts, which were determined calorimetrically and were indicative of the binding strength of lattice oxygen in the sample. The difference in dehydrogenation selectivity was also observed in the steady state experiments. These data indicated that the rate limiting and selectivity determining steps were different on these catalysts, and the selectivity for dehydrogenation was strongly affected by the binding energy of lattice oxygen.