Catalytic Oxidation Of Cyclohexane To KA-oil With Molecular Oxygen Over Hydrotalcite-based Composite Metal Oxides

Cyclohexanoland cyclohexanone(KA-oil)are important intermediates for the production of nylon-6 and nylon-66.At present,KA-oil is mainly produced by cyclohexane oxidation.Cyclohexane oxidation mainly uses the non-catalytic oxidation of molecular oxygen in the industry.The energy consumption of the method is high,the conversion per cycle of cyclohexane is only 3%to 4%,and the selectivity of KA-oil is only 80%to 82%.Therefore,for the selective oxidation of cyclohexane,it is of great significance to design an efficient,stable and environment-friendly catalyst to increase the conversion of cyclohexane and the selectivity of KA-oil.In this paper,a series of hydrotalcite-based composite metal oxide catalysts(such as Cu-MgAlO,Co-MgAlO and CuCo-MgAlO,etc.)containing different active components were prepared by co-precipitation method.The catalyst was applied to the molecular oxygen oxidation of cyclohexanereaction.The cyclohexane oxidation conditions were optimized,the stability of the catalyst was investigated,and the physical and chemical properties of the designed catalyst were determined by BET,H2-TPR,FT-IR,XRD,UV-vis,XPS and SEM.Systematic characterization was carried out to speculate that the catalyst oxidation oxidation of cyclohexane to KA-oil mechanism.First,different catalysts were selected for the selective oxidation of cyclohexane.The experimental results show that metal oxides containing Cu,Co active components have excellent catalytic properties.The stability of Cu-MgAlO in cyclohexane oxidation was investigated.The experimental results show that the catalyst exhibits high stability and good catalytic performance.The conversion rate of cyclohexane can reach 8.3%,and the selectivity of KA-oil can reach 82.9%.Second,Co-MgAlO containing different cobalt loadings was investigated.The experimental results show that 2%Co-MgAlO has excellent catalytic performance,the conversion rate of cyclohexane can reach 9%,and the selectivity of KA-oil can reach 82.3%.Finally,the catalytic properties of CuCo-MgAlO containing copper and cobalt as active components were investigated.The experimental results show that the catalytic performance of CuCo-MgAlO is not significantly different from that of Cu-MgAlO and Co-MgAlO.Therefore,it can be inferred that there is no synergy between the two metal active ingredients.The hydrotalcite-based composite metal oxide catalyst has the advantages of being cheap,easy to obtain,highly efficient,stable,and environment-friendly.The catalyst prepared in this dissertation exhibits high conversion of cyclohexane and KA oil selectivity,and has potential industrial application prospects.