| It is essential to separate ethanol from fermentation broths to ensure the continuous fuel ethanol production in the process of renewable fermentation product fuel ethyl alcohol.The traditional method for separation ethanol from water is distillation which is high energy intensived and high installation cost.Pervaporation is proposed to be one of the effective techniques for continuous ethanol recovery with Silicalite-1 membranes.Thus,the purpose of this paper is the preparation of Silicalite-1 membranes and Silicalite-1/PDMS composite membranes and investigation of their pervaporation performance for separation ethanol from water.In this paper,the Silicalite-1 seed particle preparation is firstly investigated using in situ hydrothermal synthesis.Silicalite-1 seed particles with different sizes are obtained by adjusting the formula and crystallization conditions.The flux of the Silicalite-1 membranes is improved by changing the way of crystallization.The surface of Silicalite-1 membrane is modified by PDMS in order to enhance its hydrophobicity.Lastly,the as-prepared Silicalite-1 membranes and Silicalite-1/PDMS membranes are applied to pervaporation for ethanol/water mixture.At the same time the composite Silicalite-1/PDMS membranes are applied to pervaporation for acetone/water system to expand its application.Firstly,the influence of precursor solution and crystallization conditions on the preparation of Silicalite-1 seed particles were investigated respectively and Silicalite-1 seed with the size of 0.12μm～4μm were prepared.The seed layer prepared by dip-coating and vacuum adsorption method played a role in transition,and ultimately the membrane has a certain orientation.Herein,the optimized condition is that pressure is about 0.06 MPa and the size of seed is 3μm.Secondly,the pervaporation performances of Silicalite-1 membranes were studied.The flux of the Silicalite-1 membranes prepared by the constant temperature is low,while the flux of Silicalite-1 membrane prepared by varying temperature synthesis is above 1.0 kg/(m2·h). The influence of support is investigated.The results showed that the pervaporation performance of mullite-supported Silicalite-1 membrane is better than the stain esssteel -supported andα-Al2O3-supported.The selectivity and flux of ethanol/water for mullite-supported Silicalite-1 membrane were about 42 and 3.08 kg/(m2·h). Thirdly,continuous Silicalite-1/PDMS composite membranes are prepared.PDMS layer can make up the surface defects of Silicalite-1 membrane with the concentration of PDMS solution at 5%.The thickness of PDMS layer was controlled by the vacuum and the PDMS layer with thickness of about 2μm was prepared to obtain a good performance membrane. Silicalite-1/PDMS membranes were applied in the pervaporation separation of 5%(wt%) ethanol/water mixture and acetone/water system.The composite membrane exhibits an improved separation performance with a flux of 2.67 kg/(m2·h) and separation factor of 54.9 at the ethanol content of 5wt%and 60℃.For acetone/water system at 80℃,the flux and selectivity of acetone/water were about 1.2 kg/(m2·h) and 192.
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