Kinetics of the Oxidative Dehydrogenation of Isobutance over Cr2o3／La2（CO3）3

Kinetics of the Oxidative Dehydrogenation of Isobutane over Cr2O3/La2(CO3)3

The oxidative dehydrogenation (ODH) of isobutane over Cr2O3/La2(CO3)3 has been investi- gated in a low-pressure Knudsen cell reactor, under conditions where the kinetics of the primary reaction steps can be accurately determined. By heating the catalyst at a constant rate from 150-300oC, temper- ature uctuations due to non-equilibrium adsorption are minimized. The evolved gas profiles show that ODH to isobutene and water is a primary reaction pathway, while carbon dioxide, which forms from the catalyst during reaction, is the only other product. This CO2 evolution may enhance the activity of the catalyst. Isobutene formation proceeds with the participation of lattice oxygen from the Cr2O3/La2(CO3)3 catalyst. The small pre-exponential factor is expected for a concerted mechanism and for such a catalyst with a small surface area and limited porosity.