Kinetic parameter analysis for propane ODH:: V2O5/Al2O3 and MoO3/Al2O3 catalysts

The effect of surface metal oxide loading and specific surface metal oxide species on the kinetic parameters associated with the propane oxidative dehydrogenation reaction is analyzed for several supported V2O5/Al2O3 (VAl) and MoO3/Al2O3 (MoAl) catalysts. The VAl and MoAl catalysts are synthesized and characterized to ensure the kinetic parameters are estimated primarily for the surface metal oxide phase. The kinetic parameters are successfully estimated for a consecutive Mars-van Krevelen reaction model. Analysis of the parameters reveals that the apparent pre-exponential factors for propene formation and degradation reactions increase with loading for both VAl and MoAl catalysts up to monolayer coverage with the VAl possessing larger values. However, the relative increase of the individual apparent pre-exponential factors is different. The activation energy for propene formation is relatively invariant and does not contribute to the activity comparison. The difference in activation energies for propene formation and degradation decreases with surface vanadia loading, but is relatively similar with surface molybdena loading. Detailed analysis of the kinetic parameters conclusively reveals that the surface vanadia species provides a better active site in terms of activity and propene yield for the propane ODH reaction. (c) 2007 American Institute of Chemical Engineers