Chromium(VI) supported and entrapped on silica and zirconia as recyclable materials for oxidation of alcohols

Oxidation of alcohols has been realized with Cr(VI) oxide supported or entrapped, via sol-gel methodology, on silica and zirconia. These materials were easily recovered from the reaction mixture without leaching of chromium in solution. Moreover, recycling studies have indicated that they can be regenerated by calcination at 400-600 °C or by treatment with ozone at room temperature. In the case of Cr(VI) entrapped into silica matrix up to 18 oxidation cycles have been realized wothout loss in activity.