Comparative Catalytic Behavior of Prepared Cobalt or Iron Salt of Manganese Substituted Polyoxometalate Supported on Silica in Oxidation of Benzyl Alcohol

Cobalt and iron salt of mono manganese substituted Keggin polyoxometalate have been prepared and supported on silica as heterogeneous catalysts. The prepared compounds were completely characterized by conventional techniques such as FT-IR, ICP-OES, XRD, FESEM, and BET. The results indicated that the primary Keggin structure remain intact in the obtained samples and the prepared particles were in the nanoscale. The surface area of silica support decreased after loading of the cobalt or the iron salt of mono manganese substituted Keggin polyoxometalate on it. Application of the prepared compounds for demonstration of the effect of transition metals such as cobalt (or iron) combined with mono manganese substituted polyoxometalate was investigated in solvent-free oxidation of benzyl alcohol, as a test reaction, using H2O2. The results proved that the selectivity of the silica-supported cobalt salt of mono manganese substituted Keggin polyoxometalate catalyst to benzaldehyde was more than that of the other samples. The catalyst can be reused for several runs without losing significant activity.