【作者】 颜正朝；

【导师】 林晓； 徐南平；

【作者基本信息】 南京工业大学 ， 化学工程， 2005， 硕士

【摘要】 MFI 型分子筛膜利用了MFI 沸石具有规整有序的孔道结构和优异的吸附性能的特点,已开展的研究工作表明MFI 型分子筛膜具有很好的分离效果,可望实现分子水平上的混合物分离。它在渗透汽化、气体分离和膜反应器等领域具有广阔的应用前景。随着石油资源的日渐减少,开发节能、高效的燃料乙醇生产技术已经越来越显得必要和迫切。高硅MFI 型分子筛膜（Silicalite-1）具有非常良好的乙醇/水的分离性能,高性能MFI 疏水沸石膜有望应用在生物发酵技术和渗透汽化技术耦合而成的膜生物反应器中。合成技术是MFI 型分子筛膜研究的关键,水热合成法（包括原位合成法和晶种法）是制备分子筛膜的最常用方法,本课题的研究也采用这种方法制备了MFI 型分子筛膜。研究过程中首先参考一些文献中的制备方法,用原位合成法初步合成了MFI型分子筛膜,利用XRD、SEM、EDX 和渗透汽化检测等表征手段分析了其性能及形态。并且利用热重和差热分析研究了MFI 沸石在焙烧过程中的热重变化性质,以此确定了沸石膜的焙烧程序。在此基础上,重点研究了原位合成过程中各种条件对MFI膜性能与形态的影响。通过考察各种因素的影响,我们选择了以下合成参数作为适宜的合成条件:支撑体类型,平均孔径为1μm的莫来石管;合成时间,48h;合成温度,185℃;合成液配比,n（TEOS）:n（TPAOH）:n（H₂O）=1:0.17:120;合成液搅拌时间,30min。采用经过优化后的合成条件制备的膜具有较好的性能。目前按照这种条件制备出性能最好的膜对乙醇/水体系（乙醇浓度5wt%,60℃）的分离因子为61,通量达到1.18kg/m²·h,渗透侧乙醇浓度可以提高到76.5wt%。然后,采用晶种法制备了MFI型分子筛膜。在晶种法制备过程中,考察了三种涂晶方法制备的膜的性能与形态,发现B涂晶方式效果最好。实验中还优化了晶种法德合成时间。与原位合成法相比,晶种的存在极大地影响了沸石晶体在多孔支撑体上的生长。此外,在我们目前的实验条件下,晶种法制备的性能更好。采用晶种法制备的膜的最好性能为:通量,0.85kg/m²·h;分离因子为69。更多还原

【Abstract】 Applications of MFI zeolite membranes are based on the regular channel structure and excellent sorption characteristics of MFI zeolite. The previous research works have indicated that MFI zeolite membranes have good separation performances. The membrane can be expected to realize the separation in molecular level. It has wide potential applications in fields of pervaporation, gas separation and membrane reactor. With the gradual decreasing of petroleum resources, it is more and more essential and urgent to develop an energy-conserving and high-efficient production technology of fuel ethanol. High silicon MFI zeolite membrane （silicalite-1） has a good separation performance for ethanol/water mixtures, and it can be expected to apply in membrane bioreactor coupled with fermentation and pervaporation process. Synthesis technique is the key part of MFI zeolite membrane’s research work. Hydrothermal crystallization is the most common synthesis technique for preparation of MFI zeolite membrane, including in situ growth and seeded growth methods, respectively. It was also adopted in this study. In the course of this study, first, MFI zeolite membranes were prepared by in situ growth method reported in the literature. XRD, SEM, EDX and pervaporation testing were used for characterizing these membranes. The heat and weight change of MFI zeolite powders during its calcination process was investigated by DSC and TGA,respectively,in order to optimize the calcination procedure of MFI zeolite membrane. Based on the above results, this thesis was focused on study of the influence of different factors on the morphology and property of MFI zeolite membranes prepared by in situ growth. According to the membrane characterization results, the suitable conditions for synthesis of MFI membrane are following as: mullite tube with average pore size of 1μm; synthesis time of 48 hours; synthesis temperature of 185℃; gel composition of n（TEOS）:n（TPAOH）:n（H₂O）=1:0.17:120; gel stirring time of 30 minutes. The membrane prepared under this optimized condition showed a better separation performance. Presently, the best membrane prepared by in situ growth method had a separation factor of 61 with a flux of 1.18 kg/m2·h （ethanol feed concentration of 5wt%; pervaporation temperature of 60°C）, and the ethanol concentration in the permeate side was condensed to 76.5wt%. Whereafter, the seeded growth method was applied to synthesize MFI zeolite membrane. Three seeding methods were adopted. The morphology and separation performance of these membranes were discussed, and the results showed that the method B got the best achievement. The synthesis time was also optimized. Compared with in situ growth,the seeds greatly affected crystal growth onto the porous tube. In addition, under our present synthesis conditions, the better membranes was prepared by the seeded growth method. The best membrane prepared by the seeded growth method had a separation factor of 69 with a flux of 0.85 kg/m2·h at 60°C for 5wt% ethanol solution. Although the membranes prepared in this work had a good performance, the synthesis technology needs to be further optimized in order to prepare better membrane.更多还原