β-异佛尔酮氧化反应宏观动力学研究

Study on Oxidation Kinetics of β-isophorone

作者: 专业:化学工程 导师:尹红 年度:2014 学位:硕士  院校: 浙江大学

关键词
β-IP氧化反应 气液反应 瞬间反应 气液传质

        空气氧化p-异佛尔酮(p-IP)合成茶香酮(KIP)技术使维生素E的合成原料变为丙酮而非之前的三甲酚,产生了显著的经济效益。该技术采用空气代替传统氧化剂,属于绿色化学化工研究方向。本文对β-P的氧化反应动力学进行研究,以期为工业生产提供理论指导。关于β-P空气氧化动力学参数的测定结果表明,p-IP空气氧化反应为气液瞬间反应,β-IP存在临界浓度。当β-IP的浓度高于临界浓度时,反应过程为气膜传质控制,p-P氧化反应速率与β-IP浓度呈零级关系。当β-IP的浓度低于临界浓度时,反应过程为双膜控制,主要受液膜传质控制,氧化反应速率与β-IP浓度呈一级关系。β-IP的临界浓度随氧气浓度的提高而增大。在高氧气浓度下,氧气浓度对反应速率的影响减小。空气作为氧化剂时,本文讨论了温度、搅拌转速、通气量以及搅拌桨直径等四个因素对气相体积传质系数的影响。升高温度增大了扩散系数,同时通过降低体系粘度,减少气泡聚并而增大气液比表面积以增加气相体积传质系数。增加搅拌转速可使气液混合更加充分,气液比表面积更大,从而增加气相体积传质系数。通气量增加会导致气含率增大,从而依次增大气液比表面积、气相体积传质系数和反应速率,但是反应速率增加的幅度随通气量的增加逐渐变小。固定搅拌转速不变,增大搅拌桨直径会增大单位体积输入功率,使气液比表面积增大,从而增加气相体积传质系数。综合考虑搅拌转速、通气量以及搅拌桨直径的作用得到了气相体积传质系数的关联式:ko2,GaRTd2/Do2.G=2.4×10-5(d2nρl/μl)0.9(dn2/g)0.16(ρlDl/μl)1.5(μlμg/σ)0.6(nd/μg)0.32P/PBm计算及实验结果表明,关联式计算得到的气相体积传质系数值与实验测得值接近,平均误差小于3.17%,最大误差为5.53%。纯氧作为氧化剂时,由于没有气相传质阻力,β-P氧化反应在液膜内进行,因此反应过程受液膜传质控制。本文讨论了温度、搅拌转速、通气量以及搅拌桨直径对液相体积传质系数ko2,La的影响。综合考虑搅拌转速、通气量以及搅拌桨直径的作用得到了液相体积传质系数的关联式:ko2,Lad2/Dl=4.85×102(d2nρl/μl)0.9(dn2/g)0.05(ρlDl/μl)1.5(μlμg/σ)0.6(nd/μg)0.29计算及实验结果表明,关联式计算得到的液相体积传质系数值与实验测得值接近,平均误差小于3.65%,最大误差为7.60%。
    The atmospheric oxidation of β-isophorone (β-IP) to keto-isophorone (KIP) which applies acetone instead of trimethylphenol as reactant is very important for the synthesis of vitamin E, and shows significant economic advantage. Using air as the oxidant in place of traditional oxidants has become a hotspot of green chemistry and chemical engineering. The mass transfer-reaction kinetics of β-IP oxidation is investigated in this paper to provide theoretical basis for reactor design and scale-up.The mass transfer-reaction kinetics of p-IP air oxidation was investigated in a agitator bubbling set-up. The results show that the overall reaction can be regarded as instantaneous. The overall reaction rate is only controlled by gas film and zeroth order with respect to β-IP when β-IP concentration is above the critical concentration. The overall reaction rate is controlled by dual film and first order with respect to β-IP when β-IP concentration is below the critical point. The critical concentration increases with the oxygen concentration.For β-IP air oxidation, the effects of temperature, agitator speed, aeration and impeller diameter on the overall reaction rate are investigated. The diffusion coefficient and gas-liquid interfacial area which is resulted from the decrease of the viscosity of the system and the bubble coalescence increase with reaction temperature. When the agitator speed increases, the shear stresses in the gas-liquid system increase, which leads to the increase in the gas-liquid interfacial area and gas phase volumetric mass transfer coefficient. With an increase in aeration, the gas hold-up increases, which results in the increases of the gas-liquid interfacial area, gas phase volumetric mass transfer coefficient and reaction rate in turn, However, the increase of reaction rate becomes slower when the aeration continues to increase. With an increase impeller diameter, the input power will increase under the same agitator speed, which leads to the increasing of gas phase volumetric mass transfer coefficient. A correlation equation of gas phase mass transfer coefficient combining superficial gas velocity, agitator speed and impeller diameter can be written as ko2,GaRTd2/Do2.G=2.4×10-5(d2nρl/μl)0.9(dn2/g)0.16(ρlDl/μl)1.5(μlμg/σ)0.6(nd/μg)0.32P/PBmThe calculated values according to this correlation equation are in good agreement with experimental values.The maximal average error is less than3.17%and the maximal relative error is less than5.53%.Under the condition pure oxygen,the gas phase mass transfer resistance disappears.The β-IP oxidation takes place in the liquid film and the overall reaction rate is controlled by liquid film.The effects of temperature,agitator speed,aeration and agitator diameter on the overall reaction rate are investigated.A correlation equation of liquid phase mass volumetric trransfer coefficient combining superficial gas velocity,agitator speed and impeller diameter can be written as ko2,Lad2/Dl=4.85×102(d2nρl/μl)0.9(dn2/g)0.05(ρlDl/μl)1.5(μlμg/σ)0.6(nd/μg)0.29The validation results of the correlation equation indicate that the calculated values are in good agreement with the experimental values.The maximal average error is less than3.65%and the maximal relative error is less than7.60%.
        

β-异佛尔酮氧化反应宏观动力学研究

致谢4-5
摘要5-7
Abstract7-8
1 文献综述11-31
    1.1 概述11-12
    1.2 β-异佛尔酮氧化研究现状12-13
    1.3 气液反应动力学研究进展13-27
        1.3.1 气液反应理论13-18
        1.3.2 气液反应研究装置18-27
    1.4 气液传质特征参数的测定27-30
        1.4.1 物理法27-28
        1.4.2 化学法28-30
    1.5 本文研究内容30-31
2 实验部分31-36
    2.1 实验仪器和试剂31-32
    2.2 实验装置32
    2.3 实验步骤32-33
    2.4 分析方法33-36
        2.4.1 定性分析33-34
        2.4.2 定量分析34-36
3 β-IP的空气氧化反应动力学与传质过程研究36-56
    3.1 产物结构的鉴定36-38
    3.2 β-IP空气氧化反应动力学区域的判定38-41
    3.3 瞬间反应理论41-42
    3.4 物理参数的测定42-45
        3.4.1 密度的测定42
        3.4.2 粘度的测定42-43
        3.4.3 扩散系数的估算43-44
        3.4.4 表面张力的测定44-45
    3.5 氧气浓度对β-IP氧化反应速率的影响45-48
    3.6 温度对β-IP氧化反应速率的影响48-49
    3.7 搅拌转速对β-IP氧化反应速率的影响49-50
    3.8 通气量对β-IP氧化反应速率的影响50-51
    3.9 搅拌桨直径对β-IP氧化反应速率的影响51
    3.10 气相体积传质系数关联式的求取51-54
    3.11 本章小结54-56
4 β-IP的氧气氧化反应动力学与传质过程研究56-69
    4.1 β-IP氧气氧化反应动力学区域的判定56-57
    4.2 物理参数的测定与估算57-60
        4.2.1 密度的测定57-58
        4.2.2 粘度的测定58-59
        4.2.3 扩散系数的估算59-60
        4.2.4 表面张力的测定60
    4.3 温度对β-IP氧化体系液相体积传质系数的影响60-61
    4.4 搅拌转速对β-IP氧化体系液相体积传质系数的影响61-62
    4.5 通气量对β-IP氧化体系液相体积传质系数的影响62-64
    4.6 搅拌桨直径对β-IP氧化体系液相体积传质系数的影响64
    4.7 液相体积传质系数关联式的求取64-67
    4.8 本章小结67-69
5 结论与展望69-72
    5.1 结论69-71
    5.2 展望71-72
附录72-74
作者简历及在学期间所取得的科研成果74-75
参考文献75-80


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