杂化聚酰亚胺膜气体渗透性能的模拟研究

发布时间：2018-06-24 23:35

本文选题：分子模拟 + 杂化膜　；参考：《华北理工大学》2017年硕士论文

【摘要】：目前国内外普遍关注全球变暖问题,绿色少碳成为了人们追崇的生活方式。从混合气CO2/N2中分离出CO2气体是能源及化工行业的重要分离过程,膜法分离在CO2回收中发挥着重要作用。杂化聚酰亚胺膜是将无机相掺杂到连续的高分子聚酰亚胺体系中而形成的具有无机相和有机相共同优良性质的膜材料,其突破了传统无机膜或有机膜材料研发的瓶颈。从分子结构来预测复合膜的宏观性质,进而对气体的溶解扩散性能预测成为研究热点。分子模拟技术可以缩小聚合物膜材料的研发周期,减少试验所需材料的耗费,提高效率并节约开发成本。实验并不能从聚合物的自由体积、聚合物与纳米粒子间的氢键、吸附能与吸附位等微观角度对气体的溶解扩散进行解释与表征,而分子模拟技术补充了实验存在的不足之处。以PMDA-ODA型聚酰亚胺为基本模拟单元,纳米SiO2颗粒为掺杂剂,采用COMPASS力场为势能模型,运用蒙特卡洛、分子力学与动力学方法对杂化聚酰亚胺膜(PI/SiO2)的气体渗透性能进行了研究。构建了含20个单体的等规立构高分子链,经一系列优化处理过程,获取了与实验数据相近的聚合物高分子链结构模型。分子动力学计算获取了CO2与N2在PI聚合物中的溶解、扩散与渗透的相关系数,通过XRD确定了体系的可靠性,研究发现PI分子与SiO2之间的氢键使得SiO2颗粒在PI模型中能够稳定存在,自由体积等参数的计算表明无机纳米SiO2颗粒的引入增强了膜对CO2的渗透分离性能。
[Abstract]:At present, the problem of global warming is concerned at home and abroad, and green and less carbon has become the way of life. Separation of CO _ 2 from CO _ 2 / N _ 2 mixture is an important separation process in energy and chemical industry. Membrane separation plays an important role in CO _ 2 recovery. Hybrid polyimide membrane is a kind of membrane material with excellent properties of inorganic phase and organic phase which is formed by doping inorganic phase into continuous polymer polyimide system. It breaks through the bottleneck of traditional inorganic membrane or organic membrane material research and development. The macroscopical properties of the composite membrane are predicted from the molecular structure, and the prediction of the solubility and diffusion properties of the gas becomes a hot research topic. Molecular simulation technology can reduce the research and development cycle of polymer membrane materials, reduce the cost of materials needed for testing, improve the efficiency and save the development cost. The experiments can not explain and characterize the gas dissolution and diffusion from the angle of free volume of polymer, hydrogen bond between polymer and nanoparticles, adsorption energy and adsorption site, etc. However, molecular simulation technology complements the shortcomings of the experiment. The gas permeability of hybrid polyimide membrane (Pi / Sio _ 2) was studied by Monte Carlo method using PMDA-ODA polyimide as basic simulation unit, nano-SiO _ 2 particles as dopant, and compass force field as potential energy model. The isotactic polymer chain containing 20 monomers was constructed. After a series of optimization processes, a polymer chain structure model similar to the experimental data was obtained. The correlation coefficients of dissolution, diffusion and permeation of CO _ 2 and N _ 2 in Pi polymer were obtained by molecular dynamics calculation. The reliability of the system was determined by XRD. It is found that the hydrogen bond between Pi molecule and Sio _ 2 makes the Sio _ 2 particles exist stably in the Pi model. The calculation of the free volume and other parameters shows that the introduction of inorganic nano-SiO _ 2 particles enhances the permeability and separation performance of the membrane to CO _ 2.
【学位授予单位】：华北理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ051.893

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