苯乙烯催化氧化过程的界面强化与调控研究

Due to some shortcomings in catalytic oxidation of styrene to styrene oxide and benzaldehyde by oxygen, such as long reaction time, excess oxygen emissions, difficult in control of product selectivity, and so on, the interface intensification by a jet reactor and the reaction regulation of this process is studied in this proposal. The influence of catalysts, solvent and liquid-gas ratio and other factors on the oxidation reaction are experimentally investigated to establish models of the reaction kinetics and the reaction (product) regulation. Based on the testing devices established both for the experiments of cold-model and thermal-model, the impact of the parameters of the reactor structure, operation condition, and fluid property in this oxidation system on the bubble ( group ) behavior, flow pattern, gas holdup and gas liquid interfacial area, and then mass transfer efficiency of gas-liquid interface is determined by using high-speed video camera (HVC) and particle image velocimetry (PIV) measurements, as well as the high-precision intelligent image analysis software. Therefore, the relationships between gas holdup and gas-liquid interfacial area, bubble (group) and fluid flow patterns are obtained to build the mass transfer model in the jet mixing intensification system. Through the experiments in the thermal test device, the intensification reaction models and the product regulation policy of styrene oxidation in the jet reactor can be worked out to make the process more efficient in increasing gas-liquid interfacial area and accelerating the reaction rate, as well as in regulating the product selectivity and finally utilizing raw material and energy. It will be substantially beneficial to the process design, operation and regulation of the styrene catalyzed oxidation.

本课题基于苯乙烯催化氧化制备环氧苯乙烷和苯甲醛过程反应时间长，过量氧气排放和产物选择性难控制等问题，开展液流喷射强化气液混合和产物调控研究。考察催化剂、溶剂、气液比、气液接触方式等对反应和选择性的影响，建立反应动力学模型和产物调控机制。以此为基础，在液流喷射强化冷模测试系统和热模试验系统中，综合运用高速摄像仪和粒子图像速度仪，结合高精度智能化图像识别分析软件，研究喷射强化反应器的结构参数、操作参数和物性参数等对气泡（群）行为、流型、气液界面形态、气泡直径分布、气含率和气液相界面积的影响，建立气含率和气液相界面积与结构参数、操作参数和体系物性之间的相互关系。通过热模实验，构建基于液流强制喷射反应器的苯乙烯催化氧化强化传质与反应调控模型，从而实现大幅度提高气液传质面积、加速反应过程、调控反应产物、提高原料和能源效率之目的，为苯乙烯催化氧化过程的高效强化反应器设计、操作和调控提供技术支持。

本课题基于苯乙烯氧化制备环氧苯乙烷反应时间长，过量氧气排放和产物选择性难控制等问题，开展工艺优化和反应器强化研究，以开发绿色高效的苯乙烯氧化工艺。采用纯氧氧化苯乙烯体系时，产物的总得率为72.9%，环氧苯乙烷和苯甲醛的选择性分别为53.1% 和20.7%；采用双氧水/助催化剂体系可大幅度提高环氧苯乙烷的选择性，55℃反应3h，苯乙烯的转化率96.8%，环氧苯乙烷的选择性97.7%。对两种反应体系分别建立了反应动力学方程，并采用响应曲面法对反应条件进行了优化。利用Fluent软件，分别对鼓泡反应器和气升式反应器进行CFD数值模拟，研究了不同表观气速下反应器中局部气含率、液体流速及流场等夫人变化，并将两种气-液反应器应用于优选的苯乙烯氧化反应体系中，分析了两种反应器在苯乙烯氧化方面的应用特点。研究了喷射强化反应器JILR空气-水体系和CO2-NaOH体系的流动和传质行为，明确了结构参数对气含率、气泡大小、相界面积等影响，表征了JILR的气液传质强化特性。相同操作参数下， JILR内的二氧化碳的吸收时间比鼓泡反应器缩短近一半，整体吸收转化率高出35%。在JILR中的苯乙烯氧化实验，考察了气体卷吸量、输入功率（液体流量）等参数的影响，在宏观反应动力学上对比JILR、气鼓泡反应器、升式反应器及搅拌釜反应器，明确了JILR的对于苯乙烯氧化过程的强化机理和强化效果。JILR能够产生微气泡体系，使得相界面积和液膜传质系数均有所增加，从而大幅提高了苯乙烯氧化反应的宏观反应速率。发展了高速显微摄像在线测试方法，结合图像识别分析软件研究了反应器内气泡粒径分布、气泡运动特征、气含率、气液相界面积等关键参数，以指导反应器结构优化和构效调控，从而为苯乙烯催化氧化过程的高效强化反应器设计、操作和调控提供技术支持。