Synthesis Of Silicalite-1 Membranes With Applications In Selective Permeation Of Ethanol In Its Aqueous Solution

The MFI zeolites have two-dimensional channel structure.The dynamics of the commonly used material molecular diameter are similar to silicalite-1 zeolites.It is widely used in the field of separation and catalysis.MFI zeolites have thermal stability,chemical stability and mechanical stability.Silicalite-1 belongs to the pure-silic MFI-type zeolite.Because of its high hydrophobicity,it can be used as adsorbents.Silicalite-1 membranes possess potential applications in separation of ethanol from its aqueous solution by using pervaporation.It is of great value and significance for bioethanol extraction.The synthesis methods of the homemade silicalite-1 zeolite membrane?the characterizations and its applications in separation of ethanol from its aqueous solution are studied in this paper.We first examine the influence of the seed crystals size about the silicalite-1 zeolite membranes.Then we find that the little seed crystals are more suitable for synthesis of silicalite-1 zeolite membranes.Finally we choose the seed crystals in 200 nm.The membrane synthesis method of the zeolite membrane in random orientation is secondary growth.Spin coating is the method to coat on the random orientation layer.And then we investigate the influence about the synthesis time and the temperature of the silicalite-1 zeolite membrane.Finally,in the condition of 150 ? and the 8 h growth time upward,then repeat 2 times of 16 hours growth time downward can synthetize the continuous and dense silicalite-1 membranes.Its thickness is about 5 ?m.FTIR?SEM?XRD and contact angle test characterization methods are used to study the zeolites and zeolite membranes.The application of the zeolite membranes in separation of ethanol from its aqueous solution is also studied in this paper.It uses the 5 wt.% of the ethanol/water solution for application in the experiment.When we remove the silicalite-1 membrane template agent,the membrane separation factor can reach to 23.21 with thin membrane thickness of only 5 ?m.The silicalite-1 membranes have high repetition rate,in the condition of no obvious defects,all the membranes' separation factor can reach to 15 in average.