Abstract:

The PVA/SO₄^2--AAO difunctional membranes made of polyvinyl alcohol and anodic aluminum oxide solid acid were prepared by impregnation-coating method. The structure and properties of the as-made membranes were examined by scanning electron microscope (SEM), X-ray diffraction (XRD), and NH₃ temperature programmed desorption (NH₃-TPD). The potential of the PVA/SO₄^2--AAO difunctional membranes for synthesis of ethyl acetate via esterification reaction has been explored. The effects of the loading amount of the membrane, the ratio of acetic acid to ethanol and the reaction temperature on the performance of the concerned membranes were studied. The results have shown that the conversation of ethanol could reach 87% when the ratio of acetic acid to difunctional membrane was 30:1, the ratio of acetic acid to ethanol was 4:1, the feeding temperature was 80℃, and the reaction time was 500 min. The reaction activation energy was 41.84 kJ/mol, which was 6.74 kJ/mol lower than that with the concentrated sulfuric acid as catalyst.

Key words: pervaporation, catalysis, difunctional membrane, esterification, synthesis

摘要：

采用浸渍-涂覆法制备了聚乙烯醇/阳极氧化铝固体酸（PVA/SO₄^2--AAO）催化-渗透汽化双功能膜，并用于乙酸与乙醇的催化酯化反应。用SEM、XRD、NH₃-TPD分析了双功能膜的结构及性能。考察了双功能膜用量、乙酸/乙醇摩尔比及反应温度对酯化反应转化率的影响。结果表明：乙酸/双功能膜质量比为30∶1，乙酸/乙醇摩尔比为4∶1，料液温度为80℃时乙醇的500 min转化率可以达到87%。反应活化能为41.84 kJ/mol，比浓硫酸作催化剂的经典反应活化能降低6.74 kJ/mol。

关键词: 渗透汽化, 催化, 双功能膜, 酯化反应, 合成