The Research On Biomimetic Catalytic Oxidation Of Toluene And The Industrial Synthesis Of Porphyrin

The process of toluene oxidation with air in the presence of metalloporphrin catalyst to produce benzaldehyde and benzyl alcohol has been studied in this paper. The design and installation of three stirred tank reactors in series as well as continuous experiments in laboratory scale have been carried out. The effect of metalloporphyrin catalyst on continuous oxidation of toluene as well as the influence of oxygen transfer limitations and kinetic control on biomimetic catalytic oxidation of toluene has been investigated. On basis of the biological-chemical-cycle coupling mechanism, the kinetics of biomimetic catalytic oxidation of toluene has been studied. And the corresponding kinetics mathematic model of toluene oxidation is developed firstly. Then by use of the kinetics model the experiment phenomena and the law of toluene oxidation have been analyzed quantitatively. According to the kinetics model several possible reactor models are established to optimize the oxidation reactor and reaction conditions for toluene oxidation in presence of metalloporphyrin. Finally the some chemical engineering problems of industrial synthesis of porphyrin are solved successfully. First industrial-scale synthesis of T(p-C1)PPH2and (T(p-C1)PPFe)2O has been carried out successfully in the plant designed by ourselves to produce porphyrin catalyst, and the process of industrial synthesis of cobaltporphyrin has been developed too. The main research works and results are as follows:1. The liquid-phase catalytic aerobic oxidation of toluene by metalloporphyrin is studied in a series of three stirred tank reactors. The effects of operation mode(including batch and continuous operation), catalyst and optimal catalyst concentration on the oxidation process are examined. The conversion of toluene and the selectivity to benzaldehyde and benzyl alcohol are chosen as the evaluating index. The research results are:the best catalyst is (T(p-C1)PPFe)2O and its concentration is2ppm.2. In order to determine the control step of toluene oxidation process accurately an improved technique of measuring dissolved oxygen levels for gas-liquid reaction at the elevated temperatures and pressures is used to take the sequential data in the oxidation of toluene catalyzed by metalloporphyrin. 3. Under oxygen transfer limitations and kinetic control, liquid-phase catalytic oxidation of toluene over metalloporphyrin is studied. The effect of both oxygen transfer and kinetic control on the toluene conversion and the selectivity of benzaldehyde and benzyl alcohol in biomimetic catalytic oxidation of toluene are systematically investigated. The results show that the toluene conversion under the oxygen transfer limitations is lower by2～4%(mol) than that under kinetic control under same oxidation conditions. And the total selectivity of benzaldehyde and benzyl alcohol under the oxygen transfer limitations is lower by8～10%(mol) than that under kinetic control with the same conversion of toluene. The rate of oxygen transfer doesn’t influence toluene conversion and the selectivity of benzaldehyde and benzyl alcohol under the kinetics control conditions, and toluene oxidation is zero-order with respect to oxygen. The experimental results are identical with the biomimetic catalytic mechanism of toluene oxidation over metalloporphyrin.4. On basis of the biological-chemical-cycle coupling mechanism, the kinetics of biomimetic catalytic oxidation of toluene has been studied. And the corresponding kinetics mathematic model of toluene oxidation is developed firstly. Then by use of the kinetics model the physical meaning of model parameters are analyzed in detail according to the oxidation process of toluene.5. The16kinetics model parameters are determined in a nonlinear optimization, minimizing the difference between the simulated and experimental time evolution of the product composition obtained in a batch oxidation reactor where the gas and liquid phases are well mixed, and the standard deviation of the simulated and experimental data is less than5%. The biological-chemical-cycle coupling process of toluene oxidation is explained quantitatively, the reason of high selectivity to benzaldehyde and benzyl alcohol during the toluene oxidation in presence of metalloporphrin is explained successfully according the relation of reaction activation energy.6. According to the kinetics model several possible reactor model are established to optimize the oxidation reactor and reaction conditions for toluene oxidation in presence of metalloporphyrin. The optimal results are:the conversion of toluene and the selectivity to benzaldehyde and benzyl alcohol is chosen as the evaluating index, the three continuous stirred tank reactors in series is appropriate for toluene oxidation; the optimal reaction temperature is463K,468K,473K each and average residence time of each is39min, 30min,21min; Under these reaction conditions the toluene conversion is10.07%(mol) and the selectivity to benzaldehyde and benzyl alcohol is47.57%(mol). By using the continuous mathematic reaction model for toluene oxidation with biomimetic catalyst, the maximal relative deviation between the experimental and calculated data is less than7.97%.The average relative deviation between the experimental and calculated data equals to3.69%.The reactor model predicted data for toluene oxidation systems agree with the experimental determined results satisfactorily.7. The plant to produce porphyrin catalyst has been designed and installed. The process of industrial synthesis of T(p-C1)PPH2has been optimized.The results are:the yield of T(p-C1)PPH2can reach31.90%, while the yield is only about20%in laboratory; According to kinetics of synthesis of cobaltporphyrin, a batch reaction model for synthesis of cobaltporphyrin has been established, and by use of this model the optimal synthesis conditions have been obtained successfully. Under these optimal conditions the yield of the industrial synthesis of cobaltporphrin can reach98.00%; Final the effects of reaction temperature and PH on the yield for industrial synthesis of (T(p-C1)PPFe)2O has been investigated. And the yield for industrial synthesis of (T(p-C1)PPFe)2O is more than98.00%.