A型分子筛膜的制备及其对乙酸乙酯—水体系的分离性能研究

发布时间：2018-03-22 08:10

  本文选题：分子筛膜　切入点：渗透汽化　出处：《华东理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：为了实现乙酸乙酯粗产物中二元、三元共沸体系的低能耗高效分离,采用双晶种热浸渍法在大孔α-Al_2O_3陶瓷管外表面合成了均匀致密的A型分子筛膜,并考察其对乙酸乙酯-水及乙酸乙酯-乙醇-水体系的分离效果,揭示了 A型分子筛膜的合成条件对膜结构的调控作用以及膜结构对分离性能的影响机制。首先采用水热法合成了与α-Al_2O_3陶瓷管表面孔隙相当的粒径约为2.0 μm的A型分子筛晶种L,用于修饰填补载体表面缺陷;并合成了粒径约为0.4 μm的A型分子筛晶种S,用于导向合成均匀致密的A型分子筛膜。通过优选涂晶条件、母液配比、晶化时间、晶化次数等合成工艺条件调控A型分子筛膜的结构和性能。在优化的涂晶条件下,控制母液摩尔配比为n(Al_2O_3):n(SiO2):n(Na_2O):n(H_2O)=1:5:50:1000,在晶化温度70℃、晶化时间6h的条件下可以合成结构规整、表面致密、结晶度高的厚度约为10 μm的A型分子筛膜。采用合成的A型分子筛膜对乙酸乙酯-水体系进行渗透汽化分离,考察了进料流率、操作温度对水的渗透通量及分离因子的影响,揭示了膜结构对分离性能的影响机制。在操作温度为110℃条件下,乙酸乙酯中水含量为3%时,渗透液水含量为99.68%,分离因子约为10000,渗透通量为1.72 kg/(m~2·h)。循环后渗余液中水含量可降至0.02%,达到乙酸乙酯优等品的国标要求,此时渗透液水含量为99.23%,分离因子可达210000。随着分子筛膜厚度的增加,渗透通量降低,分离因子增加。合成的高结晶度A型分子筛膜对乙酸乙酯-水体系具有优异的分离性能。与乙酸乙酯分子相比,乙醇分子因动力学直径小而更易通过A型分子筛膜,分离难度增加。合成A型分子筛膜对乙酸乙酯-乙醇-水三元共沸体系也具有较好的脱水分离性能,渗透通量为1.97 kg/(m~2·h),分离因子大于8500。
[Abstract]:In order to realize the separation of binary and ternary azeotropic system from ethyl acetate, a homogeneous and compact zeolite A membrane was synthesized on the outer surface of macroporous 伪 -Al _ 2O _ 3 ceramic tube by bimorph seed hot impregnation method. The separation efficiency of ethyl acetate water and ethyl acetate ethanol water system was also investigated. The effects of synthesis conditions on membrane structure and the mechanism of membrane structure affecting separation performance were revealed. Firstly, A with a diameter of about 2.0 渭 m equivalent to 伪 -Al _ 2O _ 3 ceramic tube surface porosity was synthesized by hydrothermal method. Type A zeolite seed L, which is used to modify and fill the surface defects of the carrier. A molecular sieve type A seed, about 0.4 渭 m in diameter, was synthesized, which was used to guide the synthesis of homogeneous and dense zeolite A membrane. The optimized coating conditions, the ratio of mother liquor and the crystallization time were used. The structure and properties of type A molecular sieve membranes were regulated by crystallization times and other synthetic conditions. Under the optimized coating conditions, under the optimized coating conditions, the structure and surface density could be synthesized by controlling the molar ratio of nnAl2O3: n / SiO _ 2: n / N _ 2O _ 2: s / N / N _ 2O / H _ 2O 1: 5: 50 / 1000 under the conditions of crystallization temperature 70 鈩，

本文编号：1647807