基于生物柴油制备的磺化聚合物复合催化膜研制及膜接触器动力学研究

In the biodiesel and the related industries of esterification, the development of novel, efficient and green catalytic technology has become the current problems of producing biodiesel for solving the traditional strong acid corrosion of equipment, producing large amounts of industrial waste water and short service life of catalyst and so on. Membrane catalytic technology, every pore of membrane as a micro-reactor, with high catalytic activity, has become green and efficient catalytic technology. The aim of the present work is to prepare a sulfonated polymer/non-woven composite catalytic membrane employing the non-woven as the inner reinforcements by the phase inversion method. The composite catalytic membrane has a higher catalytic activity, larger surface area and longer service life. The influence of membrane forming step on the membrane structure is studied with considering all relative parameters for obtaining the approach of multi-scale structural adjustment of composite membrane. And these composite membranes are loaded in fresh design of membrane contactor. The relationship between the membrane structure and catalytic performance was studied. The effects of the composite membrane structure (thickness, area, porosity, etc.), reaction temperature and the external and internal mass transfer resistances on esterification were investigated. A kinetic model of esterification was established for revealing efficient catalytic mechanism. The integrated process of esterification by the composite membrane and transesterification by a base-catalyst was for small-scale production of biodiesel from waste chicken oil and methanol, which achieved a green energy production, efficient and continuous transformation.

在生物柴油及其相关酯化产业中，传统强酸型催化剂对设备腐蚀、产生大量难处理的工业废水以及使用寿命短等难题亟待解决。开发新型高效率、长寿命催化剂及绿色催化技术成为解决当前生物柴油制备的必然选择。膜催化技术，以膜中每个微孔作为微型反应器，具有高催化活性，是绿色高效的催化技术。本项目采用相转化法制备磺化聚合物/非织造布复合催化膜并应用于制备生物柴油酯化反应。通过研究复合膜微结构调控方法及其形成机理，以实现催化活性的持久性和高效性。探索复合催化膜结构与催化性能之间的关系。考察复合膜孔隙率、膜厚度和膜层数等对其催化活性的影响规律。设计膜催化接触器，研究膜催化接触器连续催化酯化反应最佳工艺条件。研究多孔膜中的传质特性及机理研究，建立膜催化接触器中反应动力学模型，揭示高效催化机理。开发出复合膜催化酯化-甲醇钠碱催化酯交换集成工艺并连续稳定制备生物柴油，实现生物柴油生产的绿色、高效和连续化。

传统的强酸、碱均相催化法制备生物柴油会导致分离工艺复杂，设备腐蚀严重，产生大量的废酸和废碱，造成严重的环境污染。因此，开发新型高效催化技术已成为当前生物柴油制备的重要方向和研究热点。本项目以聚酯NWF为支撑材料，SPES/PES共混物为铸膜液，采用溶液相转化法制备SPES/PES/NWF复合催化膜，研究了聚酯NWF预处理、成膜条件（铸膜液浓度、凝固浴种类及组成和溶剂种类）等与复合催化膜微结构之间的关系，建立了复合催化膜微结构调控方法。场发射扫描电镜观察发现复合膜为均一的海绵状结构，断面无指状孔存在。.设计固定床膜反应器，采用SPES/PES/NWF复合膜和贯流（Flow-through）工艺连续催化制备生物柴油，考察了复合催化膜结构与催化性能之间的关系。研究发现，以油酸（酸值为200 KOH mg/g）和甲醇为原料，其质量比为3:1，反应温度为65℃，单层膜厚度为1.723mm，膜孔隙率为68%，膜面积为36.3cm2, 复合膜H+含量为15.80mmol，停留时间为162s条件下，复合膜连续催化酯化转化率可达98.2%，是浓硫酸催化效率的18倍。同时，通过假性异相催化反应动力学模型研究表明反应物在复合催化膜中的传质阻力比离子交换树脂小，催化效率高。此外，在连续500小时催化酯化反应中，复合膜催化脂肪酸制备生物柴油转化率始终保持98.0%以上，性能稳定。.假设复合催化膜Flow-through工艺连续催化制备生物柴油反应过程动力学为平推流模型，考察了反应速率及转化率与复合膜物理参数（如膜厚度、膜面积和孔隙率等）和操作条件（如体积流速、反应温度等）之间的关系，探索了反应过程传质阻力的影响规律，建立SPES/PES/NWF复合膜连续催化酯化反应动力学模型。.以鸡油为原料，建立了SPES/PES/NWF复合膜催化酯化—固体碱催化酯交换集成工艺制备生物柴油。研究表明，在最佳工艺条件即膜孔隙率为68%，反应温度为338K, 甲醇与鸡油质量比为3:1，停留时间为258 s，复合膜H+含量为25.28 mmol，采用Flow-through工艺连续催化酯化，鸡油酸值从39.52降至3.00 mg KOH/g。酯交换反应转化率为98.1%。生物柴油样品酸值、密度、粘度、闪点和凝点多项指标均满足我国GBT 20828、美国ASTM 6751-06e1和欧洲EN14214生物柴油标准。