The Preparation And Application Of Ion-exchange LTA Molecular Sieve Membranes

The pore diameter of the channel structure of LTA membrane can be changed by Ion-exchange and the performance of gas separation and liquid separation can be improved.Therefore,the study on the synthesis and separation properties of LTA molecular sieve membranes is of great significance.In this work,the pore size and flux of Cu-LTA membrane can be increased by ion exchange.First of all,LTA molecular sieve membrane was experimented by different concentration of copper acetate solution under different reaction time and temperature and then the products were tested by XRD,SEM,ICP.The most suitable reaction conditions were found for ion-exchange.Cu-LTA membrane was used for the separation of alcohol and water.SEM,XPS and XRD characterization methods was used for the Cu-LTA membrane to analysis its morphology and composition.Secondly,the separation properties of alcohol and water were measured.In addition,the gas separation performance of cesium ion exchange LTA molecular sieve membrane was investigated.The main results obtained of this work were as follows:1.The pure phase,uniform and dense LTA molecular sieve film was successfully prepared on alumina carrier by hydrothermal synthesis method.The film thickness was about 3.0?m.2.The best conditions of ion exchange was found by orthogonal experiment.To get the Cu-LTA membrane,LTA membrane was experiment at 50?with copper acetate methanol solution for 5 h.Cu-LTA zeolite membranes with thickness of about 3.0 m can be prepared without destroying the morphology of the membranes by ion-exchanged.Feed is ethanol/water mixture,in which water is10%and ethanol is 90%.Comparising the molecular sieve which is before and after ion exchange membrane.From 30?to 75?,the separation of ethanol/water before and after ion exchange coefficient are more than 1000.After ion exchange,the permeation flux of was raised.3.The two-component gas separation test of Cs-LTA molecular sieve membrane synthesized by ion exchange was carried out by soap film method,and the mixture separation factors of H2/CO2,H₂/CH₄ and H₂/C₃H₈ were 7.8,5.3 and 12.The selectivity of Cs-LTA molecular sieve membrane obtained after ion exchange to H₂/CO₂,H₂/CH₄ and H₂/C₃H₈ all exceeded the Knudsen coefficients.The influence of the separation of H₂/CO₂ mixture under different osmotic pressure was studied by soap film method.From 0.5 Bar to 2.0 Bar,the separation coefficient of H2/CO2 mixture increases with the increase of pressure.