ZSM-5分子筛膜的形成过程及其影响因素

采用打磨法在多孔-αAl2O3载体上引入尺寸为100 nm的分子筛晶种,再用水热法合成了ZSM-5分子筛膜。考察了合成液中硅铝比、水硅比和碱度等对成膜的影响,并对合成的膜进行SEM、XRD表征。结果表明,在反应液配比为n(SiO2)∶n(Al2O3)∶n(Na2O)∶n(NBA)∶n(H2O)=100.0∶1.0∶9.0∶20.0∶3 000.0时,合成分子筛膜最好,膜厚约为11μm。并通过不同时间下的膜的SEM图表征膜的成膜过程,成膜主要是液相机制起作用,即存在于溶液中硅酸根和铝酸根离子在晶种的表面上缩聚使晶体长大。

Factors Affecting the Synthesis of ZSM-5 Zeolite Membranes and Its Formation Process

The ZSM-5 membranes was synthesized on porous alumina substrates coated with nanosized ZSM-5 seeds by using manual rubbing method and then employing the hydrothermal synthesis.The effects of(n(SiO_2)∶)n(Al_2O_3), n(H_2O)∶n(SiO_2) and n(Na_2O∶SiO_2) on the membrane formation were thoroughly evaluated.The optimum reaction mixture composition is 100.0 SiO_2-1.0 Al_2O_3-20.0 NBA-9.0 Na_2O-(3 000.0) H_2O and the membrane thickness was approximately 11 μm.The formation mechanism of the zeolite membrane was shown by SEM.The crystalline mechanism of liquid phase acts as essentially.The condensation polymerization of Al(OH)_4~-and SiO_2(OH)_2~-in the reaction solution at seeds surface brought about the crystal to grow up.