大孔载体上制备NaA分子筛膜的研究

【作者】 鲁金明；

【导师】 王金渠；

【作者基本信息】 大连理工大学 ， 化工工艺， 2004， 硕士

【摘要】 NaA分子筛膜具有0.3～0.5nm的有效孔径、三维的孔道结构和很强的亲水性，在小分子及低碳烃类气体分离和有机物脱水方面有巨大的应用前景。而在大孔载体上无法合成高质量的NaA分子筛膜制约着它在工业上的应用。针对这个问题，本论文考察了水热合成法及微波合成法制备NaA分子筛膜的规律，结合两者的优点，提出了一种新方法——微波修饰法，应用这种方法制备出性能良好的NaA分子筛膜。 本论文利用正交实验考察了影响NaA分子筛膜制备的因素，得到制膜的最佳实验条件。同时，还考察了影响膜放大合成的多个因素，对晶种的引入方式进行了全面的分析，提出了新的引入晶种的方法——热浸渍法，经过SEM及气体渗透表征，证明热浸渍法引入晶种，明显提高了在大孔载体上制备NaA分子筛膜的质量。结合正交实验结果，得到放大制备NaA分子筛膜的合成条件，在孔径为3～5μm、长250mm、外径为12mm的大孔载体管上放大制备了NaA分子筛膜，经过XRD、SEM及气体渗透实验表征，证明所合成的膜为致密、连续、完整、渗透率高并具有一定分子筛分功能的NaA分子筛膜，其氢气的渗透率为9.3×10^-7 mol·m^-2·s^-1·Pa^-1，H₂／N₂、H₂／C₃H₈的分离因数分别为5.1和10.3，高于努森扩散时的3.74和4.76。将所合成的NaA分子筛膜应用于乙醇／水渗透蒸发实验，考察了温度及压差对其性能的影响，得到了膜管在最佳工艺条件下的渗透量为1.16kg／m²h^-1，乙醇与水的分离因数为1054。 采用正交实验考察了微波条件下NaA分子筛的合成规律，经过修正后得到最佳实验条件，应用于NaA分子筛膜的制备，得到了具有一定分子筛分功能的NaA分子筛膜(α_N2／H2=6.5)。同时还考察了不同阶段、不同载体处理方法及不同焙烧温度对膜的影响规律。 分析并结合水热合成与微波合成的特点，提出一种新方法——微波修饰法。采用此方法在大孔载体上制备得到了NaA分子筛膜，经过XRD、SEM及气体渗透实验表征，结果表明，NaA分子筛膜致密、完整无缺陷，氢的渗透率为3.22×10^-6 mol／m²·Pa·s，氮氢分离因数达8.2，高于水热法(α_H2／N2=5.1，氢渗透率为9.3×10^-7 mol／m²·Pa·s)和微波法(α_H2／N2=6.5，氢渗透率为1.5×10^-7 mol／m²·pa·s)的合成结果。进行重复实验，证明微波修饰法具有较好的重复性。 本论文还对水热合成法、微波合成法及微波修饰法制备NaA分子筛膜的生成机理进行了探索，对今后在大孔载体上NaA分子筛膜的制备有一定的借鉴作用。更多还原

【Abstract】 The efficient pore size of NaA zeolite membranes is between 0.3nm and 0.5nm, which has three-dimensional open-framework and high hydrophilicity. The application perspectives of NaA zeolite membrane are very great in separation of small molecules and low hydrocarbon gases and dehydration of organic solution. However, it restricts its application in the industry that high quality NaA zeolite membrane can not be prepared on the macropore supports. Aiming at this problem, the preparation rules of NaA zeolite membrane synthesized by hydrothermal synthesis and microwave synthesis were investigated in this thesis. Integrating hydrothermal synthesis with microwave synthesis, the new method, microwave-adjusting method, was brought forward, and the high quality NaA zeolite membranes were prepared by this method.The best experimental conditions were found through orthogonal experiments which studied the factors affecting the preparation of NaA zeolite membrane. Moreover, some factors which can affect the enlarging preparation of NaA zeolite membranes were investigated. The methods of introducing seeds were analyzed fully and the new method to introduce seeds, the hot dip-coating, was brought forward. NaA zeolite membranes were characterized by SEM and pure gas permeation measurement, which showed that it improved clearly the quality of NaA zeolite membrane prepared on the macropore supports to introduce seeds on supports using hot dip-coating. Integrating the results of orthogonal experiment with the factors effecting enlarging membrane, the best experimental condition of enlarging preparation of membrane was found. Adopting this experimental condition, NaA zeolite membrane was prepared on macropore tubular support which is 250mm long and its pore size is 3~5u.m and outer-diameter is 12mm. Characterized by XRD SEM and pure gas permeation measurement, NaA zeolite membrane was proven it is dense, continuous, integral, high permeation and has certain molecular sieving property. The permeation of the hydrogen of the membrane is 9.3x10-7 mol m-2 s-1 Pa-1 and the ideal selectivity of H2/N2 H2?C3H8 were 5.1 and 10.3 respectively, which are both over the value of knusen, 3.74 and 4.76. The NaA zeolite membrane was applied to the removal of water from ethanol/water mixtures by pervaporation, and the effects of temperature and difference pressure on the property of membrane were investigated. The total flux of permeance is 1.16kg/m2h-1 and the selectivity is 1054 under the best operating condition.The preparation rules of NaA zeolite under microwave heating were investigated by orthogonal experiments. Further adjusted, the best experimental conditions was found, which was applied to prepare NaA zeolite membrane. The membrane had certain molecular sieving property (an2/h2=6.5). Furthermore, the effects of different stages, method of treatingsupports and baking temperature were studied.Analyzing and Integrating hydrothermal synthesis with microwave synthesis, the new method, microwave adjusting method, was brought forward, and the high quality NaA zeolite membranes were prepared by this method on the macropore supports. Characterized by XRD, SEM, pure gas permeation measurement, NaA zeolite membrane was proven it is dense, continuous, integral and no defect. The permeation of the hydrogen of the membrane is 3.22x10-6 mol m-2 s-1 Pa-1, and the ideal selectivity of H2/N2 was 8.2 , which were both over the values of membrane synthesized by hydrothermal synthesis(aH2/N2=5.1, The permeation of the hydrogen was 9.3x10-7 mol/m2Pas) or by microwave synthesis(aH2/N2=6.5, The permeation of the hydrogen was 1.5x10-7 mol/m2 Pa s). Repeating the experiment, it showed microwave-adjusting method had good repeatability.The formation mechanisms of membrane prepared by hydrothermal synthesis, microwave synthesis and microwave adjusting method were explored in this thesis which can benefit to prepare NaA zeolite membrane on the macropore supports for the future.更多还原