Cyclohexane Oxidation With Hydro Peroxide Over Supported Au Catalysts

Cyclohexanone and cyclohexanol (KA oil) are important raw materials for the production of adipic acid and caprolactam. The greater demand for these oxidation products and the high-energy intensity of the present process warrant a replacement with a more effective catalytic process. The increased environmental concerns in recent years call for benign oxidants such as molecular oxygen or hydrogen peroxide was used as the oxidant.In the present work, Au catalysts supported on various resins were prepared using an incipient wetness impregnation technique, and their catalytic performances in cyclohexane oxidation using hydro peroxide as an oxidant were investigated. The results show that Au catalysts supported on the IRA400 resin exhibit excellent activity and selectivity. A highly efficient oxidation of cyclohexane to cyclohexanol and cyclohexanone could be accomplished in acetone solvent at 65℃and atmosphere; 15.6% cyclohexane conversion, 83.6% selectivity of cyclohexanol and cyclohexanone, and the ratio of cyclohexanone to cyclohexanol 4.1 were achieved over 0.1wt%Au/IRA400 catalyst. X-ray diffraction (XRD), X-ray photoelectron energy spectrum (XPS), UV-Vis diffuse reflection (UV/Vis), transmission electron microscopy (TEM), et al. were used to characterize the catalysts.In addition, Au catalysts supported on metal oxides and active charcoal were synthesized, characterized and tested in cyclohexane oxidation. The results show that Au catalysts supported on graphite prepared by deposition-precipitation method exhibits the best catalytic performance. Over 3wt%Au/Graphite catalyst, 13.9% cyclohexane conversion, 83.8% selectivity of cyclohexanol and cyclohexanone, and the ratio of cyclohexanone to cyclohexanol 3.1 were achieved under the optimum reaction conditions (in acetone solvent at 90℃and atmosphere for 4 h). This catalyst could be reused at least five recycles without obvious loss of the catalytic activity and selectivity.