Preparation And Application Of Catalytic-pervaporation Difunctional Membrane In Ethyl Acetate Synthesis

Catalytic pervaporation difunctional membranes refer to the composite membranes which have the functions of catalytic and pervaporation. Combining the reaction and separation will simplify the technological processes, and that can be reduced equipment investment and operating cost. The preparation of PVA/SO42--AAO difunctional membrane with impregnation method was studied using PVA as the separation layer and SO42--AAO as the catalyst. And the prepared membrane was applied to the synthesis of ethyl acetate.The main contents are as follows:(1) According to differential PVA concentration, kinds of PVA/AAO pervaporation membranes with the AAO supporting layer and PVA separation layer with different thickness were prepared. The structure and separation performance of membranes were characterized by scanning electron microscope(SEM), water contact angle and pervaporation separation of different ethyl acetate-water mixtures at different temperature,respectively. The results show that the water flux and separation factor could reach2727g/(m2h) and 37945 respectively for PVA/AAO composite membrane with 3wt.% PVA concentration separating 0.5wt.% ethyl acetate aqueous at 50?.(2) With the SO42--AAO as solid catalyst and supporting layer and PVA as separation layer, the PVA/SO42--AAO difunctional membrane was prepared by impregnation method.The structure and properties of prepared membranes were tested by SEM, X-ray diffraction(XRD), NH3 temperature programmed desorption(NH3-TPD), X-ray Photo-electronic Spectroscopy(XPS). The pervaporation and catalytic performance of difunctional membranes were tested, respectively. The results show that the difunctional membrane with 2mol/L sulfuric acid owns the best higher catalytic activity and separation performance.(3) The prepared PVA/SO42--AAO difunctional membrane was used to coupling esterification reaction synthesized ethyl acetate with separation process. The effects of amount of membrane, feed composition and reaction temperature to reaction conversation were studied. The results show that at the condition of 2mol/L sulfuric acid, the ratio of acetic acid to difunctional membrane is 30:1, n(acetic acid):n(ethanol)=4:1 and temperature of 80?, the conversation of ethanol could reach 87%. And there was no acetic acid and ethyl acetate in penetrants. It demonstrates that the difunctional membranes realize the coupling of catalytic reaction and separation process broke the equilibrium of reaction, promote the catalytic reaction to positive and improve the reactant conversation.