Direct Evidence for Active Support Participation in Oxide Catalysis: Multiple Operando Spectroscopy of VOx/Ceria

Ceria-supported vanadia is catalytically active in oxidative dehydrogenation (ODH) reactions. Here, we provide direct spectroscopic evidence for the participation of the ceria support in the redox catalysis. To unravel the structural dynamics of vanadia/ceria (VOx/CeO2) catalysts during ethanol ODH, we have applied a combination of operando multiwavelength Raman and operando UV-vis spectroscopy. Our approach consists of the targeted use of different Raman excitation wavelengths, enabling the selective enhancement of ceria (at 385 nm) and vanadia (at 515 nm) vibrational features. As part of the support dynamics, ceria lattice oxygen is shown to directly participate in the ODH reaction, while V-O-Ce interface bonds are broken during substrate adsorption, resulting in ethoxide formation. The presence of V-O-Ce bonds is considered to be crucial for the observed synergy effect in catalytic performance, allowing ceria to act as an oxygen buffer stabilizing the vanadium center. By providing an experimental basis for a detailed understanding of working VOx/CeO2 catalysts, our results highlight the importance of active support participation in oxide catalysis.