Studies On The Performance Regulation Of Mesoporous Cadmium Sulfide Supported Protoporphyrin Cobalt And Manganese For Catalyzing Oxidation Of Cyclohexane

In order to simulate the axial coordination between cysteine and center iron ions of heme in cytochrome P-450 enzyme and its cavity function,the catalytic performance of metal protoporphyrin was fully utilized.Mesoporous biomimetic materials obtained by axial coordination were used to catalyze the oxidation of cyclohexane.Coordinating and supporting metal porphyrins(Co PP and Mn PP)on the cavity of mesoporous cadmium sulfide(mp-CdS)carrier to form mesoporous biomimetic materials(Co PP/mp-CdS and Mn PP/mp-CdS),and controling the internal and external factors of catalytic materials by response surface methodology(RSM)to catalyze the oxidation of cyclohexane with molecular oxygen.The work content and main results of this study are as follows: 1.Mesoporous cadmium sulfide(mp-CdS)was prepared,and mesoporous biomimetic catalytic materials(Co PP/mp-CdS and Mn PP/mp-CdS)were prepared by axial coordination 2.The morphology,thermal stability and structure of the catalytic materials were analyzed by various characterization methods.3.(1)Four key factors(reaction temperature,oxygen pressure,catalyst weight,ratio of porphyrin molecular surface area to carrier surface area(TSAR))affecting the catalytic oxidation of cyclohexane over mesoporous biomimetic catalytic materials(Co PP/mp-CdS and Mn PP/mp-CdS)were preliminarily explored by traditional single factor method(TOM).The cyclic performance of Co PP/mp-CdS was tested.The results show that the catalyst could be recycled for 5 times,which showed better catalytic performance and cycle performance than the corresponding unsupported metalloporphyrin.(2)On the basis of TOM method,response surface methodology was used to optimize the internal factors of catalytic materials and the external influence conditions of catalytic cyclohexane oxidation(namely,taking the above four factors as variables and conversion% as response value).four factors and three levels box Behnken experiments were conducted.Under the optimized conditions of two methods(TOM and RSM),the conversion of cyclohexane oxidation catalyzed by Co PP/mp-CdS was 35.78% and 45.77%,respectively,which was increased by 27.98% under the optimized control of RSM method.For Mn PP/mp-CdS catalytic oxidation of cyclohexane,the conversion was 34.45% and 48.19% under the two methods(TOM and RSM),respectively.Under the optimized control of RSM method,the conversion of cyclohexane was increased by 39.85% by Mn PP/mp-CdS.The cyclic performance test under RSM method showed that the two catalysts could catalyze cyclohexane oxidation for 6 times,which showed better catalytic performance and cycle performance than the corresponding original metalloporphyrin.The average conversion and yield of alcohols and ketones obtained by Mn PP/mp-CdS were higher than those which obtained by Co PP/mp-CdS.The results show that the catalytic performance of Mn PP/mp-CdS is better than that of Co PP/mp-CdS,that is to say,strengthening the axial coordination and optimizing the internal and external factors affecting the catalytic performance will be beneficial to the improvement of the catalytic activity of metalloporphyrins.4.According to the experimental results and related literature,the mechanism of cyclohexane oxidation catalyzed by mesoporous cadmium sulfide supported metal protoporphyrin was discussed,and the mechanism of cyclohexane oxidation catalyzed by mesoporous cadmium sulfide supported metalloporphyrin was preliminarily determined as free radical reaction mechanism.