Preparation And Application Of High Performance Zeolite T Membrane

Membrane separation technology applied in the dehydration of organic matter has an important demand in industry.Zeolite T with Si/Al ratio 3⁴ and pore size 0.36 nm×0.51nm possess good acid-resistance while remaining hydrophilic,which suitable for the dehydration of isopropanol and ethanol.The separation performance of zeolite T membrane for ethanol/water system was improved by adjusting the synthesis path and membrane microstructure.This paper explored the influencing factors of zeolite T membrane synthesis,further by introducing fluorine mineralizer to improve the pervaporation performance of the membrane,and creatively used gel conversion method to prepare zeolite T membrane,which containg ERI phase and OFF phase that the performance to dehydration of ethanol of the zeolite T membrane has improved greatly.The main contents of the experiment are as follows:1.The molar ratio of the synthetic solution was 1 SiO₂:0.05 Al₂O₃:0.26 Na₂O:0.09 K₂O:35 H₂O.The effects of stirring method,crystallization method and silicon source on the separation performance of zeolite T membrane by hydrothermal secondary method were investigated.Under the conditions of magnetic stirring,static crystallization and Ludox as-40silicon source,the best flux and separation factor of zeolite T membrane for 90 wt.%ethanol/water at 75℃is 1.26 kg·m^-2·h^-1and 834 respectively.2.By adding fluorine mineralizer in synthetic system to improve the separation performance of zeolite T membrane.The effects of fluoride concentration and water ratio on the performance of the membrane were investigated.The optimized synthesis gel was obtained as 1 SiO₂:0.05Al₂O₃:0.26 Na₂O:0.09 K₂O:a MF（3 NaF:1 KF）:b H₂O.Tracked the growth process of zeolite T membrane,found that the synthesized membrane was formed by epitaxial growth and the thickness is consistent with seeds layer is about 3⁴μm.Under optimized conditions,the flux and separation factor of zeolite T membrane to 90 wt.%ethanol/water at 75℃is 2.68 kg·m^-2·h^-11 and 9164 respectively.3.In order to strengthen the epitaxial growth of zeolite T membrane,innovative in using gel conversion method to prepare zeolite T membrane,and fluoride salt content,water content,the influence of silica content on the membrane were investigated,the optimal molar ratio of the synthetic solution was 1 SiO₂,Al₂O₃ 0.05:0.26 Na₂O:K₂O:0.09 m MF（3 NaF:1KF）:n H₂O.The pervaporation performance of the synthesized membrane were really high to dehydrate the 90 wt.%isopropanol and ethanol solution at 75℃,the flux were 6.09 and 4.27kg·m^-2·h^–11 respectively and separation factor were both bigger than 10000.Trace the effect of crystallization time on the process and performance of preparing zeolite T membrane,and put forward the mechanism of enhanced seed epitaxial growth method for preparing zeolite T membrane by gel conversion method.Water molecules act from inside out to avoid the generation of cracks,so as to synthesize dense and continuous membrane,so its performance is improved effectively.4.The influence of the temperature of the feed liquid and the concentration of ethanol on the pervaporation performance of the zeolite T membrane was investigated.With the increase of the feed liquid temperature,the flux of water and ethanol increased,and the separation coefficient also increased.As the concentration of ethanol in the feed solution increases,the flux decreases obviously,while the separation coefficient first decreases slightly and then increases.