Physical studies of MoO3 catalysts on silica and carbon supports

The nature and characteristics of the catalytic surface of supported MoO₃ catalysts were studied. Changes that occurred on oxidizing alcohols in air over carbon and silica supported MoO₃ were examined. Structural data were combined with electron microscopy and photoelectron spectroscopy to demonstrate that the carbon support promotes segregation and fragmentation of MoO₃, whereas sintering occurs on silica. Results indicated that this may be correlated with a synergism between the carbonaceous material and metal oxide which provides a reoxidation pathway for reduced Mo, thus preventing formation of extended zones of MoO₂, which is inactive for the oxidation of alcohols.