无模板剂法制备MFI型分子筛膜
发布时间：2018-07-23 11:58
【摘要】：Silicalite-1(纯硅MFI型)分子筛膜是一种具有良好热稳定性和化学稳定性的无机微孔材料,且具有高硅铝比和高疏水性等特性,因此在渗透蒸发分离乙醇/水混合液方面有很好的前景。传统的合成方法需要加入有机模板剂,然后通过煅烧脱除。而在高温煅烧过程中,由于分子筛层与载体之间的热膨胀系数不同或者晶格参数的改变使分子筛膜产生缺陷,从而影响分子筛膜的性能。本工作采用无模板剂二次生长法在α-Al_2O_3载体上合成出连续的MFI分子筛膜,并应用于渗透蒸发分离低浓度乙醇/水溶液。 本工作制备了两种不同大小的silicalite-1分子筛晶种,采用旋涂法制备晶种层。先在有模板剂合成液中生长后,然后在无模板剂合成液中形成MFI型分子筛膜。通过SEM、XRD、IR、CO_2/N_2双组分气体分离、乙醇/水溶液分离等手段对所合成的分子筛膜的性能进行检测。 对于600 nm晶种层,先在组成摩尔比为1 TEOS: 0.2 TPAOH: 800 H_2O的有模板剂合成液中水平向上生长,合成温度为150°C;然后在180°C下,在组成摩尔比为1 TEOS: 0.40 NaOH: 270 H_2O的无模板剂合成液中合成MFI型分子筛膜。晶化程序为6+16*+16* h(*代表无模板剂中的生长时间)制备的分子筛膜效果最好,其结晶度较高,气体分离系数为1.138,乙醇/水的分离系数为2.115。 对于200 nm晶种层,采用与前者相同的步骤合成的分子筛膜渗透通量较小。在摩尔组成为1 TEOS: 0.25 NaOH: 180 H_2O的无模板剂合成液中,经过8+24* h晶化后形成的分子筛膜效果最好,其乙醇/水分离系数为1.264,渗透通量为2.383 kg·m~(-2)·h~(-1)。 实验结果表明,200 nm分子筛颗粒的晶种层在载体表面排列更加紧密,而且晶种层也较平整,但是600 nm分子筛颗粒的晶种层合成膜时所形成的无定形物较少,而且乙醇/水分离的效果更好。
[Abstract]:Silicalite-1 (pure silicon MFI) molecular sieve membrane is a kind of inorganic microporous material with good thermal stability and chemical stability, and has the characteristics of high Si-Al ratio and high hydrophobicity, so it has a good prospect in permeating evaporation separation of ethanol / water mixture. Traditional synthesis methods require the addition of organic templates and then removal by calcination. In the process of high temperature calcination, because of the difference of thermal expansion coefficient between the molecular sieve layer and the carrier or the change of lattice parameters, the molecular sieve membrane is defective, thus affecting the performance of the molecular sieve membrane. In this work, continuous MFI molecular sieve membranes were synthesized on 伪 -Al2O3 carrier by the second growth method without template, and were used to separate low concentration ethanol / aqueous solution by osmotic evaporation. In this work, two kinds of silicalite-1 molecular sieve seeds with different sizes were prepared, and the seed layer was prepared by spin coating method. The MFI molecular sieve membrane was formed in the synthesis solution with template and then in the synthesis solution without template. The properties of the synthesized molecular sieve membranes were tested by means of SEMX XRDX / IRCO2 / Nac _ 2 two-component gas separation and ethanol / aqueous solution separation. For the 600 nm seed layer, the synthesis temperature is 150 掳C, and then at 180 掳C, the templating agent synthesis solution with a molar ratio of 1 TEOS: 0.2 TPAOH: 800 H2O is grown horizontally. MFI molecular sieve membranes were synthesized in a template-free synthesis solution with a molar ratio of 1 TEOS: 0.40 NaOH: 270H _ 2O. The molecular sieve membrane prepared by the crystallization procedure of 6 16 * 16 * h (* representing the growth time without template) has the best effect with high crystallinity, the gas separation coefficient is 1.138, and the separation coefficient of ethanol / water is 2.115. For the 200 nm seed layer, the permeable flux of the zeolite membrane synthesized by the same steps as the former is relatively small. In the template-free synthesis solution composed of 1 TEOS: 0.25 NaOH: 180H2O, the molecular sieve membrane formed after crystallization for 8 24 * h was the best. The ethanol / water separation coefficient was 1.264 and the permeation flux was 2.383 kg m-2 h-1. The experimental results show that the seed layer of 200 nm molecular sieve particles is more closely arranged on the surface of the carrier, and the seed layer is more smooth, but the amorphous material formed by the seed layer of 600 nm molecular sieve particles is less. Moreover, ethanol / water separation is more effective.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：O643.3
本文编号：2139339
[Abstract]:Silicalite-1 (pure silicon MFI) molecular sieve membrane is a kind of inorganic microporous material with good thermal stability and chemical stability, and has the characteristics of high Si-Al ratio and high hydrophobicity, so it has a good prospect in permeating evaporation separation of ethanol / water mixture. Traditional synthesis methods require the addition of organic templates and then removal by calcination. In the process of high temperature calcination, because of the difference of thermal expansion coefficient between the molecular sieve layer and the carrier or the change of lattice parameters, the molecular sieve membrane is defective, thus affecting the performance of the molecular sieve membrane. In this work, continuous MFI molecular sieve membranes were synthesized on 伪 -Al2O3 carrier by the second growth method without template, and were used to separate low concentration ethanol / aqueous solution by osmotic evaporation. In this work, two kinds of silicalite-1 molecular sieve seeds with different sizes were prepared, and the seed layer was prepared by spin coating method. The MFI molecular sieve membrane was formed in the synthesis solution with template and then in the synthesis solution without template. The properties of the synthesized molecular sieve membranes were tested by means of SEMX XRDX / IRCO2 / Nac _ 2 two-component gas separation and ethanol / aqueous solution separation. For the 600 nm seed layer, the synthesis temperature is 150 掳C, and then at 180 掳C, the templating agent synthesis solution with a molar ratio of 1 TEOS: 0.2 TPAOH: 800 H2O is grown horizontally. MFI molecular sieve membranes were synthesized in a template-free synthesis solution with a molar ratio of 1 TEOS: 0.40 NaOH: 270H _ 2O. The molecular sieve membrane prepared by the crystallization procedure of 6 16 * 16 * h (* representing the growth time without template) has the best effect with high crystallinity, the gas separation coefficient is 1.138, and the separation coefficient of ethanol / water is 2.115. For the 200 nm seed layer, the permeable flux of the zeolite membrane synthesized by the same steps as the former is relatively small. In the template-free synthesis solution composed of 1 TEOS: 0.25 NaOH: 180H2O, the molecular sieve membrane formed after crystallization for 8 24 * h was the best. The ethanol / water separation coefficient was 1.264 and the permeation flux was 2.383 kg m-2 h-1. The experimental results show that the seed layer of 200 nm molecular sieve particles is more closely arranged on the surface of the carrier, and the seed layer is more smooth, but the amorphous material formed by the seed layer of 600 nm molecular sieve particles is less. Moreover, ethanol / water separation is more effective.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：O643.3
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