Ethane and Propane Oxidation over Supported V2O5/TiO2 Catalysts:  Analysis of Kinetic Parameters

The effect of surface vanadia loading on the alkane (ethane and propane) oxidation reaction kinetics for supported V2O5/TiO2 catalysts is investigated by employing a parallel−sequential Mars−van Krevelen model. Analysis of the kinetic parameters reveals that the preexponential factors for alkene formation and alkene combustion reactions increase with vanadia loading, except for CO2 formation from ethene. Furthermore, the activation energy for ethene formation appears to be greater than that for propene. The values of the rate constant ratios k 1/k 2 and k 1/(k 3 + k 4), which represent the amount of alkane available and the net alkene formed, are functions of vanadia loading and alkanes oxidized, and are closely related to the ratio of the respective preexponential factors. The highest k 1/(k 3 + k 4) value, which corresponds to the highest alkene yield at isoconversion, is observed for the monolayer catalyst and is higher for propene formation than for ethene formation.