Preparation and characterization of V2O5/MgO catalysts for selective oxidation of 4-methylanisole to anisaldehyde

A series of V₂O₅/MgO catalysts containing 1 to 20 wt % V₂O₅ were prepared and characterized by means of X-ray diffraction, FT-infrared, electron spin resonance, scanning electron microscopy, NH₃ and CO₂ uptake measurements. Activity and selectivity of the catalysts were evaluated for selective oxidation of 4-methylanisole to p-anisaldehyde. Characterization results suggest that the vanadia when impregnated on magnesia interacts strongly with the support and results in the formation of a magnesium orthovanadate compound instead of two-dimensional over layers on the support surface. The V−Mg−O compound formed exhibits good conversion and product selectivity for the title reaction. Attempts are made to correlate the acid-base characteristics of the catalysts, obtained from NH₃ and CO₂ uptakes, with their catalytic properties.