静电纺丝制备多孔纳米纤维及其催化酯化反应的应用

发布时间：2018-07-25 18:05

【摘要】：以静电纺丝方法制备的一维连续纳米纤维膜作为纳米催化剂的载体,可以解决纳米材料难以回收的难题,而纤维间微米级的孔结构降低了使用过程中的传质阻力,使其成为一种优良的催化剂载体。通过在纺丝溶液中加入无机盐碳酸氢钠(NaHCO3),可以在纳米纤维表面形成中孔(2-50nnm)及大孔(50nm以上)结构,进一步提高纤维膜的比表面积和孔隙率。通过热处理的方法不仅可以提高纤维膜的机械性能,而且能使纳米纤维表面孔结构发生收缩。将PFSA阳离子树脂以浸渍法和热处理负载并固定于纤维膜之上,酸化后用于乙酸乙酯的催化酯化反应。研究结果如下：首先,研究了NaHCO3对纳米纤维形貌的影响,随着添加量的增加,经酸洗去除NaHCO3的纤维膜比表面积和孔隙率有显著提高,孔径分布曲线中最可几孔径由小于10nm的转变到50-70nm之间,且孔体积明显提高,最大值达到0.288cm3.g-1。其次,通过浸渍和热处理的方式将PFSA负载固定于纤维膜上,通过其孔径分布dD-dLogD曲线看出,经热处理后,300nm以下孔结构收缩明显,而且孔体积有一定程度下降。复合纤维膜离子交换能力最高有0.445mmol/g,PFSA离子交换能力的利用率高达88.6%,且复合纤维膜回收率均在96%以上,再次活化后其离子交换能力基本保持初始状态,说明通过浸渍法和热处理法负载PFSA树脂于纤维膜上具有优良效果和可行性。最后,通过催化酯化的评价实验发现,浸渍法制备的复合纤维膜催化剂效果优于共混法,随着催化剂用量的提高,最高1小时转化率即接近90%,其反应动力学常数最高可达5.267×10-4m3·kmol-1s-1·g-1,优于同类型商业化酸性阳离子树脂。
[Abstract]:The one-dimensional continuous nanofibrous membrane prepared by electrostatic spinning method as a carrier of nano catalyst can solve the difficult problem of recovery of nanomaterials. The microporous structure between fibers reduces the mass transfer resistance in the process of use and makes it a good catalyst carrier. By adding hydrogen carbonate to the spinning solution, the hydrogen carbonate is added to the spinning solution. Sodium (NaHCO3) can form the mesoporous (2-50nnm) and the large pore (50nm) structure on the surface of the nanofiber, and further improve the specific surface area and porosity of the fiber membrane. By heat treatment, the mechanical properties of the fiber membrane can be improved and the surface structure of the nanofibers can be contracted. The PFSA cation resin is impregnated and heat. The catalytic esterification reaction of ethyl acetate was carried out after acidification and immobilized on the fiber membrane.
First, the effect of NaHCO3 on the morphology of nanofibers was studied. With the increase of the amount of addition, the specific surface area and porosity of the fiber membrane removed by acid washing were significantly improved. The most possible aperture in the pore size distribution curve was changed from less than 10nm to 50-70nm, and the pore volume increased obviously, the maximum value reached to 0.288cm3.g-1. next, through impregnation. The PFSA load was immobilized on the fiber membrane by heat treatment. Through the dD-dLogD curve of its pore size distribution, it was found that after heat treatment, the structure of the pore structure under 300nm was contracted obviously, and the pore volume decreased to a certain extent. The maximum ion exchange capacity of the composite fiber membrane was 0.445mmol/g, and the utilization of PFSA separation capacity was as high as 88.6%, and the composite fiber was used as a composite fiber. The recovery rate of the membrane is above 96%. After reactivation, the ion exchange capacity is basically kept in the initial state. It shows that the PFSA resin loaded by impregnation and heat treatment has excellent effect and feasibility on the fiber membrane. Finally, through the evaluation experiment of catalytic esterification, it is found that the effect of the composite fiber membrane catalyst prepared by the impregnation method is better than that of the blending method. With the increase of the amount of catalyst, the maximum conversion rate of 1 hours is close to 90%, and the reaction kinetic constant is up to 5.267 * 10-4m3. Kmol-1s-1. G-1, which is better than the commercial acid cation resin of the same type.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ340.64;TB383.1

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