Partial oxidation of ethanol on vanadia catalysts on supporting oxides with different redox properties compared to propane

The influence of the support material of vanadia catalysts on the reaction rate, activation energies, and defect formation enthalpies was investigated for the oxidative dehydrogenation of ethanol and propane. Characterization by infrared absorption–reflection spectroscopy (IRAS), Raman and UV–vis spectroscopy verifies a high dispersion of vanadia for powder and thin-film model catalysts. The support effect of ceria, alumina, titania, and zirconia is reflected in activation energy, oxidative dehydrogenation (ODH) rate, and temperature-programmed reductions (TPR) for both catalyst systems, ethanol and propane. Impendence spectroscopy and density functional theory (DFT) calculations were used to determine the defect formation enthalpy of the vanadyl oxygen double bond, providing the scaling parameter for a Bell–Evans–Polanyi relationship. On the basis of a Mars–van-Krevelen mechanism, an energy profile for the oxidative dehydrogenation is proposed.

The influence of the support material of vanadia catalysts on reaction rate, activation energies, and defect formation enthalpies of the vanadyl oxygen bond was investigated for the oxidative dehydrogenation of ethanol and propane. A relationship following a Bell–Evans–Polanyi principle was found between defect formation enthalpy and activation energy.Figure optionsDownload high-quality image (68 K)Download as PowerPoint slideHighlights
► Support effect is found in powder as in thin-film model catalysts.
► Support effect is proven by density functional theory (DFT) calculations.
► Linear correlation found between apparent activation energies of ethanol and propane.
► Activation energies follow Bell–Evans–Polanyi (BEP) principle with defect formation enthalpies.