Studies On The In-situ Hydrothermal Synthesis Of Silicalite-1 Film And Its Separation Performance

In the coal chemical industry,the organic waste water produced by F-T synthesis process?such as oil and water separation,air flotation and gas extraction?remains a large content alcohol.The azeotrope,which consists of alcohol and water,is very difficult to separate and remove.It is a pure silica zeolite without aluminum.The structure of Silicalite-1 film membrane exhibits MFI skeleton topology and there is no electrostatic cation in the structure.At the same time,The Silicalite-1 film membrane zeolite possesses good hydrophobicity property.Therefore,it has been widely applied in the separation field.In this study,Silicalite-1 film membrane was prepared by in-situ hydrothermal synthesis on the porous quartz carrier surface with TPAOH as template.The orientation of static and dynamic Silicalite-1 film was compared.The samples were characterized by scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,Fourier transform infrared spectroscope?FT-IR?,infrared spectrometer X-ray diffraction?XRD?.The gas chromatography?GC-920?was employed to determine the pervaporation separation performance of Silicalite-1 molecular sieve membrane under low concentration ethanol water system.In order to obtain the optimal conditions of synthesizing Silicalite-1 film,the effects of water content,stirring time and stirring intensity,crystallization time and crystallization temperature on the crystal structure,size and orientation of zeolite were investigated.The results showed that the most suitable condition to synthesize Silicalite-1 molecular sieve and dense b-oriented film is that the synthesis of liquid mole ratio is 1TEOS:0.2TPAOH:80H₂O,the stirring time is 24h,the crystallization temperature is 170?and the crystallization time is 3h.Then,the method of situ hydrothermal rotation is used to prepare dynamic synthesis of Silicalite-1 molecular sieve membrane.The results of SEM,XRD and FT-IR shows that the prepared Silicalite-1 zeolite membrane is random crystal orientation in dynamic rotationcondition and the thickness is two times than that of static hydrothermal condition.The reason is good crystal dispersion,short crystallization time,and scoured the carrier surface by synthetic fluid.In addition,the study showed that static osmotic membrane and dynamic synthesis of synthetic membrane flux maximum in the same infiltration time was5.053Kg·m^-2·h^-1and 1.52Kg·m^-2·h^-1and the separation factors were 7.52 and 3.14,when the raw material temperature is 60?and the suspension concentration is 5%.Hence,the penetrated performance depends on the orientation of molecular sieve crystal.