疏水微介孔Me-SiO_(2)改性silicalite-1膜用于脱醇性能研究

Dealcoholization performance of hydrophobic micro-and mesoporous Me-SiO_(2) modified silicalite-1 membranes

在大孔α-Al_(2)O_(3)载体上采用二次水热生长法制备silicalite-1沸石膜。为了弥补沸石膜的缺陷并提高其疏水性,利用甲基三乙氧基硅烷(MTES)和正硅酸四乙酯(TEOS)水解共聚后的杂化有机硅Me-SiO_(2)对沸石膜进行修饰改性。结果表明,形成的Me-SiO_(2)溶胶平均粒径18 nm,经N_(2)吸脱附等温线测试,表明其具有微介孔性质(孔径1.5和3.0 nm);经凝胶化后形成疏水性的Me-SiO_(2)/silicalite-1复合膜,其厚度分别为500 nm/10μm,表面静态接触角可达134°。在渗透汽化分离低质量分数乙醇/水时,经Me-SiO_(2)修饰的silicalite-1膜渗透侧的水通量约为未修饰前的1/4,而在增加的膜层阻力下乙醇通量仍然得到保持甚至提高。这说明Me-SiO_(2)修饰了膜的亲水缺陷,增强了乙醇的吸附和对水的排斥,从而提高了脱醇性能。通过优化溶胶质量分数,2.0%Me-SiO_(2)溶胶修饰silicalite-1膜的分离性能达到最佳,在温度为60℃、质量分数为5%乙醇/水溶液中,渗透通量达到4.3 kg×m^(-2)×h^(-1),分离因子为24.5。

Silicalite-1 zeolite membranes were prepared by a secondary hydrothermal growth method on macroporousα-Al_(2)O_(3) support.In order to improve defects and hydrophobicity,the zeolite membranes were modified by Me-SiO_(2) sols prepared via hydrolysis and copolymerization of methyl triethoxy silane(MTES)and tetraethyl orthosilicate(TEOS).The results show that the average particle size of the Me-SiO_(2) sols is 18 nm,and it has micro-mesoporous structures(1.5 and 3.0 nm)analyzed by N_(2) adsorption-desorption isotherms.The hydrophobic Me-SiO_(2)/silicalite-1 composite membranes were formed with a composite thickness of 500 nm/10μm and surface static contact angles up to 134°after gelation.In pervaporation of low-concentration ethanol/water,the water flux on the permeate side of the Me-SiO_(2) modified silicalite-1 membrane was 4 times lower than that of the unmodified one,while the ethanol flux was maintained or even increased with increased layer resistance.The results indicate that Me-SiO_(2) layer reduced hydrophilic defects,which enhances ethanol adsorption and water repulsion.2.0%Me-SiO_(2) modified silicalite-1 membranes showed optimized separation performance.In the pervaporation of 5%ethanol/water mixtures at 60,the permeation flux was 4.℃3 kg×m^(-2)×h^(-1) with a separation factor of 24.5.