跨临界CO2反应装置催化酯化-分离耦合制备松香酯反应机理

Using rosin, the rich biomass resources in Guangxi, as raw materials, the reaction mechanism of a self-inventive method about rosin ester preparation by coupling of catalytic esterification and separation in a transcritical CO2 reaction system will be studied. Using greenhouse gas (CO2) as green catalyst and separating agent, the water formed by the esterification process will be constantly taken out of the esterification reactor based on the self circulation technology of transcritical CO2 expansion and compression to eliminate the feedback inhibition caused by the products accumulation. Then, the rosin esterification-separation coupling mechanism will be discussed. The law of transfer process will be investigated using the on-line detecting system formed by laser holographic interferometry and infrared thermometer and thermography monitoring, particle imaging velocimetry, gas distributor, visual-high pressure reactor and computer, and the volumetric mass transfer coefficient model and the heat transfer coefficient model will be obtain, moreover, the relationship among gas flow rate, interface thickness, concentration and temperature distribution can be discussed. The relationship among the gas distribution pipe size, ventilation flow rate, ventilation direction and cavitation number will be investigated by ventilated cavitation experiment combined with numerical simulation method, and the formation of supercavity and the drag reduction mechanism will also discussed. The structure of each component in the reaction system and the changes of their concentration will be online tracked, and then the reaction network diagrams and lumped kinetic model of the complex rosin esterification system will be established. Furthermore, the reaction mechanism of resin acid esterification, which is catalyzed by ScCO2 and hot water proton acid, can be discussed. These will provide theoretical foundation for a highly efficient green and clean way of resource utilization and development of forestry and agricultural.

以广西优势生物质资源松香为原料，对自主创新发明的跨临界CO2反应装置催化酯化-分离耦合制备松香酯方法进行反应机理研究。采用CO2作为绿色催化剂和分离剂，应用跨临界CO2膨胀-压缩自循环技术使酯化生成的水不断地原位移出反应器，消除产物累积而引起的反馈抑制作用，探讨松香酯化反应-分离耦合机理；采用激光全息干涉/红外测温热像-粒子成像测速-气体分布器-可视高压反应器-计算机在线数据采集技术研究传递过程规律，建立体积传质与给热系数模型，揭示气体流速-界面厚度-浓度-温度分布规律；采用通气空化实验-数值模拟法考察气体分布器尺寸-通气/方向-空化数之间的关系，探讨反应器内超空泡的形成与减阻机制；在线跟踪测试反应体系结构及浓度变化，构建松香酯化复杂体系集总反应网络和动力学模型，探讨ScCO2-高温水生成质子酸催化树脂酸酯化反应机理，为开辟一条高效绿色清洁的农林生物质资源深加工新途径和新方法提供理论依据。

松香酯是松香化学深加工中最重要的品种之一，针对传统制备方法中使用酸触媒以及相际传递困难等问题，进行绿色催化-分离耦合制备松香酯的研究。采用改进的高温相平衡装置测定松脂体系相平衡数据，建立了相平衡的活度系数模型和pH计算模型，进行松香酯化反应热动力学的研究，获取了反应活化焓和活化熵，探讨超/亚临界(Super/subcritical,Sup/sub)CO2-H2O促进树脂酸酯化的热力学机制，发现富含CO2-高温H2O催化剂减少了酯化反应所需的热量输入。采用快速控温-压力变送器节流实验系统，测定了CO2-H2体系单一/混合工质的节流热力学效应，应用立方型状态方程进行节流热效应分析，绘制温度转化曲线，为跨临界CO2膨胀-压缩自循环技术提供热力学依据。采用恒温恒压-可视化-通气控制-实时高速成像两相流场实验系统研究松脂溶液中CO2气泡行为，获取气泡运动参数和气泡上升速度的变化规律，确定了气泡速度及曳力系数的最佳预测模型为Tomiyama模型，发现气液传质过程中随着溶液黏度的增加，CO2运动轨迹的振荡减弱，为明晰反应体系的减阻规律提供理论依据。以Sup/subCO2-水为绿色催化剂和分离剂、高温高压跨临界反应装置及跟踪采样-GPC技术，进行松香酯化反应特性和复杂反应动力学研究，考察有无CO2、Sup/Sub CO2下产生超空泡效应促进传递的不同环境中树脂酸的酯化反应效果，为高品质松香酯的绿色化制备提供理论依据；以松香和木糖醇为原料、Sup/subCO2-高温H2O为绿色催化剂制备木糖醇酯生物质基表面活性剂，研究了它的表面活性特性、自组装行为、热力学特性和食品乳化性能；构建Sup/SubCO2-H2O催化松香/氢化松香酯化的反应历程图，建立了幂型连串反应动力学模型，为反应器的设计提供理论依据。进行Sup/SubCO2-H2O催化松香树脂酸酯化反应机理研究，建立基于气液平衡、电荷平衡及化学平衡的pH计算模型，发现反应体系pH值为3.49～4.57，关联PCO2-T-pH值-酯化率的关系，探讨了高压CO2于高温水中形成质子酸代替酸催化酯化反应的机理，表明CO2的加入可降低体系的活化能和焓，从而提高反应速率，提出了Fischer 酯化机理、碳酸质子化醇以及CO2-醇形成高度亲核物质促进松香酯生成的三种酯化反应机理。

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