CS-PVAPVDF膜蒸汽渗透强化乙酸异丙醇的酯化反应.docVIP

CS-PVA/PVDF膜蒸汽渗透强化乙酸异丙醇的酯化反应 王 静，李卫星，邢卫红 (南京工业大学 材料化学工程国家重点实验室，江苏 南京210009) 摘要：实验室制备的CS-PVA/PVDF）中空纤维复合膜，用于蒸汽渗透耦合乙酸异丙醇酯化反应。通过扫描电镜表征膜的微观结构。研究了复合膜在蒸汽渗透下分离水/异丙醇的性能。考察了耦合酯化反应过程中反应温度、催化剂用量、醇酸初始摩尔比以及膜温对酯产率和膜通量的影响。结果表明：膜分离层与支撑体结合紧密；复合膜对水/异丙醇体系具有较好的分离性能酯化反应的最佳条件：反应温度95，醇酸摩尔比2.5:1，催化剂用量3%，膜温90。反应1 h，酯收率由非耦合时的82.7%提高到耦合时的99.2% 关键词：CS-PVA/PVDF；乙酸；异丙醇；蒸汽渗透 中图分类号：TQ028.8文献标识码：A 文章编号： of acetic acid and isopropanol by CS-PVA/PVDF composite membrane WANG Jing，LI Weixing，XING Weihong State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 210009, China) Abstract: The hollow fiber composite membrane chitosan-poly (vinyl alcohol)/polyvinylidene fluoride (CS-PVA/PVDF) was prepared and applied in esterification of acetic acid and isopropanol coupled with vapor permeation (VP). The microstructure of the membrane was characterized by scanning electron microscope (SEM) and the separation performance of membrane was investigated. Effects of various operating conditions including reaction temperature, catalyst loading, initial molar ratio of acetic acid to isopropanol and membrane temperature were considered. Results indicated that the separation layers were successfully coated onto the supports and the membrane exhibited high efficiency in separating water from water/isopropanol mixture. The optimized conditions were reaction temperature of 95 ℃, initial molar ratio of acetic acid to isopropanol of 1:2.5, catalyst loading of 3 wt% and membrane temperature of 90 ℃. Under the optimized conditions, the yield of isopropyl acetate increased from 82.7% to 99.2% with VP at 11.5 h. Key words: chitosan-poly (vinyl alcohol)/polyvinylidene fluoride (CS-PVA/PVDF); acetic acid; isopropanol; vapor permeation 酯化反应是重要的精细化工过程，合成的酯类物质广泛应用于溶剂、涂料、医药和化妆品等领域。但是，酯化反应是可逆反应，受热力学平衡的限制，平衡转化率不高。目前，提高转化率的常用的方法主要是增大反应物中某一组分的量或者将反应与精馏耦合，但是这2种方法存在反应速率低、产物分离难和能耗较高的缺点。近年来，蒸汽渗透膜分离技术因节能、环保、分离效率高及能耗低的优点，引起了广泛的关注[错误！未找到引用源。]。Li等[4]采用蒸汽渗透耦合乙酸正丙醇酯化反应，乙酸的转化率由78.2%提高到98.6%。在酯化反应过程中，选用亲水性