無模板劑法制備MFI型分子篩膜
發(fā)布時間：2018-07-23 11:58
【摘要】：Silicalite-1(純硅MFI型)分子篩膜是一種具有良好熱穩(wěn)定性和化學(xué)穩(wěn)定性的無機微孔材料,且具有高硅鋁比和高疏水性等特性,因此在滲透蒸發(fā)分離乙醇/水混合液方面有很好的前景。傳統(tǒng)的合成方法需要加入有機模板劑,然后通過煅燒脫除。而在高溫煅燒過程中,由于分子篩層與載體之間的熱膨脹系數(shù)不同或者晶格參數(shù)的改變使分子篩膜產(chǎn)生缺陷,從而影響分子篩膜的性能。本工作采用無模板劑二次生長法在α-Al_2O_3載體上合成出連續(xù)的MFI分子篩膜,并應(yīng)用于滲透蒸發(fā)分離低濃度乙醇/水溶液。 本工作制備了兩種不同大小的silicalite-1分子篩晶種,采用旋涂法制備晶種層。先在有模板劑合成液中生長后,然后在無模板劑合成液中形成MFI型分子篩膜。通過SEM、XRD、IR、CO_2/N_2雙組分氣體分離、乙醇/水溶液分離等手段對所合成的分子篩膜的性能進(jìn)行檢測。 對于600 nm晶種層,先在組成摩爾比為1 TEOS: 0.2 TPAOH: 800 H_2O的有模板劑合成液中水平向上生長,合成溫度為150°C;然后在180°C下,在組成摩爾比為1 TEOS: 0.40 NaOH: 270 H_2O的無模板劑合成液中合成MFI型分子篩膜。晶化程序為6+16*+16* h(*代表無模板劑中的生長時間)制備的分子篩膜效果最好,其結(jié)晶度較高,氣體分離系數(shù)為1.138,乙醇/水的分離系數(shù)為2.115。 對于200 nm晶種層,采用與前者相同的步驟合成的分子篩膜滲透通量較小。在摩爾組成為1 TEOS: 0.25 NaOH: 180 H_2O的無模板劑合成液中,經(jīng)過8+24* h晶化后形成的分子篩膜效果最好,其乙醇/水分離系數(shù)為1.264,滲透通量為2.383 kg·m~(-2)·h~(-1)。 實驗結(jié)果表明,200 nm分子篩顆粒的晶種層在載體表面排列更加緊密,而且晶種層也較平整,但是600 nm分子篩顆粒的晶種層合成膜時所形成的無定形物較少,而且乙醇/水分離的效果更好。
[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 偽 -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 擄C, and then at 180 擄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.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2010
【分類號】：O643.3
本文編號：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 偽 -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 擄C, and then at 180 擄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.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2010
【分類號】：O643.3
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