Selective Aerobic Oxidation Of Cyclohexane In Liquid Phase By A Novel Partially Graphitic Carbon

The selective oxidation of cyclohexane to cyclohexanol and cyclohexanone (KA oil) by using air/oxygen as the oxidant is of extreme importance in the chemical industry, because cyclohexanol/cyclohexanone are highly demanded in industry for the production of polymers, insecticide/herbicide, plasticizer, and pharmaceuticals. To date, the biggest challenge in commercialized processes is the difficulty on controlling the selectivity, since both cyclohexanone and cyclohexanol are easier to be oxidized compared to cyclohexane. Industrially, to prevent the over-oxidation to organic acids (adipic acid), the conversion of cyclohexane is controlled not more than5%and this thereby causes such problem as low efficiency and high energy consumption.A novel partially graphitic carbon was synthesized in this work to act as an effective catalyst for the selective oxidation of cyclohexane in liquid phase. Raman, TEM and XRD tests are used to determine the graphitization structure and amorphous carbon structure in the materials. TG result reveals that there is2wt%of cobalt salt left in the carbon. This material exhibited an excellent catalytic performance in the aerobic oxidation of cyclohexane in liquid phase. The conversion of cyclohexane reached41.7%with a high selectivity of47.5%to KA oil and29.8%to AA after reaction at130℃for8h. To the best of our knowledge, this result is much higher than that of most of solid catalysts reported. Further study shows that the co-existence of graphitic structure and amorphous counterpart may account for the excellent catalytic activity. The graphitic part may take part in the activation of oxygen and then cause the spillover for the further reaction to the amorphous part, which plays an important role in the good selectivity to KA oil.In Chapter4, an S/N-co-doped carbon material was prepared by a simple grinding method. Thus-prepared material was characterized by elemental analysis, XRD, TEM, FT-IR, etc., and tested as the catalyst towards aerobic oxidation of cyclohexane. The conversion can mount to23.9%with40.7%selectivity of KA oil and24.9%selectivity of adipic acid.