Highly selective liquid-phase aerobic oxidation of vanillyl alcohol to vanillin on cobalt oxide (Co3O4) nanoparticles

Abstract

Spinel Co₃O₄ nanoparticles prepared by solution phase method having particle size in the range of 12–20 nm exhibited excellent activity for the liquid-phase aerobic oxidation of vanillyl alcohol with 80% conversion and 98% selectivity to vanillin. Our catalyst could be reused three times without appreciable loss in activity. The catalytic activity of the Co₃O₄ nanoparticles was found to be similar to its homogenous precursor (cobalt acetate) and greater than the commercial Co₃O₄ oxide. The detailed characterization results of morphology, size and structure of the prepared Co₃O₄ nanoparticles obtained by XRD, FT-IR, H₂-TPR, HR-TEM and cyclic voltammetry technique were used to understand the roles of various Co species in directing the selectivity towards vanillin.