Catalytic Oxidation Of Cyclohexane To KA-oil Over Supported V, Fe, And Co Catalysts

KA oil?mixture of cyclohexanol and cyclohexanone?has a widly range of applications in the fields of pesticides,pharmaceuticals,coatings and detergents,and is also an essential intermediate for the production of nylon-6 and nylon-66.In the traditional industrial process,KA oil is mainly prepared by non-catalytic oxidation and catalytic oxidation of cyclohexane.The conversion of cyclohexane is usually lower than 5%in order to obtain high selectivity of KA oil,resulting in lower oxidation efficiency and higher energy consumption.Therefore,developing a highly efficient and eco-friendly catalyst for the selective aerobic oxidation of cyclohexane to KA oil is highly desirable in chemical industry.Firstly,supported hydrotalcite-derived vanadium metal catalyst?V/MgAlO?is prepared by impregnation method by using V₂O₅ as active component.The physico-chemical properties of the designed catalyst are systematically characterized by XRD,H₂-TPR,FT-IR,UV-vis,XPS,SEM and BET.Under the optimal conditions of reaction temperature 150 ^oC,oxygen pressure 0.6 MPa and reaction time 2 h,6.9%of cyclohexane conversion with 80.4%of selectivity to KA oil is obtained.However,the catalyst was easy to be agglomerated during the reaction.In addition,the supported cobalt catalyst over nitrogen-doped carbon?Co/N-C?is synthesized by the pyrolysis of metal complex.The microstructure of catalyst is characterized by FT-IR,XRD,UV-vis,XPS,SEM,and so on.The Co/N-C catalyst exhibits excellent catalytic performance,6.5%of cyclohexane conversion with 84.2%selectivity to KA oil is obtained under the optimal reaction conditions.Moreover,Co/N-C catalyst also displays high stability in the aerobic oxidation of cyclohexane.Finally,the iron-cobalt bimetallic catalyst supported on the modified carbon?Fe-Co/N-C?is also prepared.The physico-chemical properties of the designed catalyst are systematically characterized by BET,XRD,XPS and Raman spectroscopy.The results indicated that 6.5%conversion and 83.0%selectivity to KA oil are obtained under the optimal conditions.Likewise,the catalyst exhibits excellent stability and catalytic performance in this oxidation process.In summary,the supported cobalt catalysts over nitrogen-doped carbon with good stability and excellent catalytic performance were successfully prepared,and have potential industrial application prospects.This work is also helpful for developing better catalysts for the selective aerobic oxidation of cyclohexane.