论文总字数：21759字

摘 要

乙酸乙酯在化工生产中有着广泛的应用。目前工业上生产乙酸乙酯存在着转化率低、能耗大等问题。渗透汽化催化复合膜同时具有良好的催化和分离功能。与一般化工生产中的单一催化过程或者单一分离过程相比，渗透汽化催化复合膜缩小反应器的体积，降低了生产成本，因而引起了广泛的关注。本文选用了聚乙烯醇（PVA）为分离层膜材料，戊二醛（GA）为交联剂。选用酸性离子液体作为反应催化剂，制备催化复合膜，并用于渗透汽化耦合乙醇和乙酸的酯化反应。

实验中考察了PVA浓度、不同水含量的乙醇水溶液等对分离层分离性能的影响。同时考察了催化剂浓度、PVA浓度对催化复合膜耦合乙酸乙酯合成反应的影响。通过红外（FT-IR）、热重分析（TG）对膜的微观结构和理化性质进行表征。结果表明：分离不同含量的乙醇水溶液时，随着原料中水含量增加，渗透通量增大，分离因子减小。水含量达到10 wt%时，渗透通量180 g·m^-2·h^-1，分离因子为126。热重分析显示：当温度大于300 °C膜具有良好的热稳定性。红外光谱图证明了ILs成功接枝到PVA膜上。

最后优化了制膜条件。最佳的制膜条件为：分离层中PVA含量为5%，催化剂用量为30%，分离层中PVA最佳含量为5%。最佳反应条件下，反应温度为75 ºC，乙酸的转化率为93%。

关键词：聚乙烯醇；渗透汽化；催化复合膜；酯化反应；离子液体

Preparation and Characterization of Polyvinyl Alcohol Pervaporation Catalytic Composite Membranes for Esterification

Abstract

Ethyl acetate has a wide range of applications in chemical production. The current industrial production of ethyl acetate has problems such as low conversion rate and high energy consumption. Pervaporation catalytic composite membrane has good catalytic and separation functions at the same time. Compared with a single catalytic process or a single separation process in general chemical production, the pervaporation catalytic composite membrane reduces the volume of the reactor and reduces the production cost, thus causing widespread concern. In this paper, polyvinyl alcohol (PVA) was used as the separation membrane material and glutaraldehyde (GA) as the cross-linking agent. The acidic ionic liquid was selected as a reaction catalyst to prepare a catalytic composite membrane and used for the pervaporation esterification reaction of coupled ethanol and acetic acid.

The effects of PVA concentration and different water content of ethanol aqueous solution on the separation performance of the separation layer were investigated. At the same time, the effect of catalyst concentration and PVA concentration on the coupling reaction of ethyl acetate to the catalytic composite membrane was investigated. The microstructure and physicochemical properties of the films were characterized by infrared (FT-IR) and thermogravimetric analysis (TG). The results showed that the separation flux decreased with the increase of the water content in the raw material, the increase of the permeation flux and the decrease of the separation factor. When the water content reaches 10 wt%, the permeation flux is 180 g•m-2•h-1 and the separation factor is 126. Thermogravimetric analysis shows that the film has good thermal stability when the temperature is greater than 300 °C. IR spectra demonstrated successful grafting of ILs onto PVA membranes.

Finally, the membrane conditions were optimized. The optimum conditions for membrane preparation are: the PVA content in the separation layer is 5%, the amount of catalyst is 30%, and the optimum content of PVA in the separation layer is 5%. Under the optimal reaction conditions, the reaction temperature was 75 °C, and the conversion of acetic acid was 93%.

KEYWORDS: Polyvinyl alcohol; Pervaporation; Catalytic composite membrane; Esterification; Ionic liquid

目 录

摘 要 I

Abstract II

第一章 文献综述 1

1.1 乙酸乙酯 1

1.1.1 乙酸乙酯的性质 1

1.1.2 乙酸乙酯的用途 1

1.2 乙酸乙酯生产方法 1

1.2.1 乙酸酯化法 1

1.2.2 乙醛缩合法 1

1.2.3 乙烯加成法 2

1.2.4 乙醇脱氢法 2

1.3 渗透汽化 2

1.3.1 渗透汽化技术 2

1.3.2 渗透汽化膜材料 4

1.4 催化复合膜的制备方法 6

1.5课题研究目的与意义 7

第二章 实验部分 8

2.1 渗透汽化分离膜 8

2.1.2 实验药品和仪器 8

2.1.2 制膜步骤 9

2.1.3 实验装置及步骤 9

2.1.4 分析方法 9

2.2 催化复合膜 11

2.2.1 实验药品和仪器 11

2.2.2 实验装置及步骤 12

2.2.3 制膜步骤 12

2.2.4 分析方法 12

2.2.5 催化复合膜的表征 13

第三章 实验结果及讨论 14

3.1 分离层的实验结果及讨论 14

3.1.1 PVA浓度对分离层的影响 14

3.1.2不同水含量对分离层渗透汽化性能的影响 14

3.1.3分离层的实验小结 15

3.2 催化复合膜的实验结果及讨论 15

3.2.1 催化复合膜的红外分析 15

3.2.2 催化复合膜的热重分析 16

3.2.3 催化层中PVA浓度的影响 17

3.2.4 催化剂浓度的影响 19

3.2.5 催化复合膜的实验小结 20

第四章 结论 22

4.1 结论 22

4.2 建议 22

参考文献 23

致 谢 27

文献综述

乙酸乙酯

1.1.1 乙酸乙酯的性质

乙酸乙酯化学式C₄H₈O₂，为无色透明液体，低毒性，能与多数有机溶剂互溶，能吸水分，使其缓慢水解而呈酸性反应。密度0.902 g/mL；熔点189.55 K；沸点350.25 K；粘度0.426。

1.1.2 乙酸乙酯的用途

乙酸乙酯在化工生产中有着广泛的应用，主要用于医药、涂料、化妆品等领域^[1]。乙酸乙酯还可用作提取剂和萃取剂。

1.2 乙酸乙酯生产方法

工业上常用的生产乙酸乙酯的方法主要有四种^[2]，分别为酯化法、缩合法、加成法和脱氢法。

1.2.1 乙酸酯化法

用乙酸、乙醇为原料，在强酸作用下羟基与羧基发生缩聚反应，生成乙酸乙酯。

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