无模板剂耐酸性ZSM-5沸石膜的制备及在渗透汽化脱水中的应用

发布时间：2018-03-02 18:07

  本文选题：ZSM-5沸石膜　切入点：异丙醇脱水　出处：《武汉科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：渗透汽化是一种高效率、低能耗、投资少的新型环保膜分离技术，其分离过程不受汽-液平衡的限制，特别适合共沸物的分离，广泛应用于有机物脱水尤其是醇类有机溶剂脱水的研究。ZSM-5沸石膜具有很高的热稳定性、耐酸性、离子交换性和良好的选择性，是理想的渗透汽化膜分离材料。通过适宜路线制备高质量ZSM-5沸石膜已成为膜研究的热点。 本文采用二次生长法，无模板剂条件下在α-Al2O3载体上制备ZSM-5沸石膜，用异丙醇/水体系评价膜的渗透汽化性能。研究了晶种浓度、晶化次数、晶化时间、Si/Al摩尔比和F/Si摩尔比对ZSM-5沸石膜渗透汽化性能的影响，确定出两次预涂晶种，两次晶化合成，n(F/Si)=0.9；n(Si/Al)=7的ZSM-5沸石膜制备方法。通过优化膜的合成时间、晶种浓度、涂晶温度等条件，提高了膜的渗透汽化性能，，可制备出高通量高选择分离性的ZSM-5沸石膜，其渗透通量高达1.106kg·m-2·h-1，分离因数高达24991。 用优化条件下制备的ZSM-5沸石膜进行热稳定性和耐酸性测试，结果表明在不同的温度条件下ZSM-5沸石膜的分离因数均在1×104以上，说明其有很高的热稳定性。在pH约为5.8酸性环境中，考察了操作温度对沸石膜渗透汽化性能的影响。当操作温度为70℃，进料乙酸乙酯浓度约为97wt.%时，渗透通量可达0.287kg·m-2·h-1，分离因数可达3790。在pH约为5.8的乙酸乙酯溶液中浸泡10d后，其渗透汽化分离因数为7894，说明ZSM-5沸石膜具有一定的耐酸性。 用制备的ZSM-5沸石膜对异丙醇水溶液进行脱水浓缩，在进料异丙醇浓度约为80wt.%、操作温度为70℃条件下，脱水浓缩48h后，异丙醇浓度升高至99.613wt.%，渗透液水含量保持99wt.%以上，表明ZSM-5沸石膜可以高效分离水和异丙醇。
[Abstract]:Pervaporation is a new environmentally friendly membrane separation technology with high efficiency, low energy consumption and low investment. The separation process is not restricted by vapor-liquid equilibrium, and is especially suitable for the separation of azeotrope. ZSM-5 zeolite membrane has high thermal stability, acid resistance, ion exchange and selectivity. It is an ideal material for pervaporation membrane separation, and the preparation of high quality ZSM-5 zeolite membrane by suitable route has become a hot spot of membrane research. In this paper, ZSM-5 zeolite membrane was prepared on 伪 -Al _ 2O _ 3 carrier without template by secondary growth method. The pervaporation performance of the membrane was evaluated by isopropanol / water system. The effect of Si / Al molar ratio and F / Si molar ratio on pervaporation performance of ZSM-5 zeolite membrane was determined. The preparation method of ZSM-5 zeolite membrane was obtained by twice pre-coated seed and twice crystallization. The pervaporation performance of the membrane was improved under the condition of coating temperature, and the high flux and high selectivity ZSM-5 zeolite membrane was prepared. The permeation flux was 1.106 kg 路m-2 路h-1 and the separation factor was 24991. The thermal stability and acid resistance of the ZSM-5 zeolite membrane prepared under the optimized conditions were tested. The results showed that the separation factor of the ZSM-5 zeolite membrane was above 1 脳 10 ~ 4 at different temperatures. The effect of operating temperature on the pervaporation performance of zeolite membrane was investigated in pH 5.8 acid environment. When the operating temperature was 70 鈩

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