优先透过CO2的金属有机骨架-聚酰亚胺纳米复合膜的设计制备研究

Membrane separation technology is an efficiency approach for CO2 separation and capture. However, the issues of low gas permeance and poor permselectivity of CO2 separation membrane have been limited its application. In this work, the combination of functionalized organic linker and solvothermal synthesis with postsynthetic method was proposed to prepare nanoscale metal-organic frameworks (MOFs)control with special functionalities. In order to optimize the nanoscale functionalized-MOFs synthesis, the mechanism of the functionalized-MOFs formation was investigated. Based on the above investigation, the naoscale functionalized-MOFs crystals were incorporated into the polyimide membrane layer by the combination of self-assembly with phase transformation method. The structure of composite membrane was observed and analyzed to investigate the mechanism of MOFs-polyimide nanocomposite membrane formation. The gas permeance properties of the nanocomposite membrane was studied to reveal the relation ship between the membrane structure and separation performance. In addition, the permance mechanism of the membrane was discussed by the combination of computer simulation. The nanocomposite membrane with high permeance and high selectivity as well as high stability was controllably fabricated for preferential CO2 capture and separation. The present study will show important application value in the environment and gas separation. Moreover, this work is very important in opening a new route in the combination of organic chemistry and inorganic chemistry with computer simulation science.

膜分离技术是温室气体CO2分离、捕获的一条有效途径。然而CO2分离膜的通量和选择性低的难点和问题，成为制约CO2分离膜推广应用的瓶颈。本课题采用功能化的有机配体、溶剂热和后处理集成的方法，研究含有特定基团的纳米金属有机骨架（MOFs）材料可控合成，并探讨其形成的机制，可控合成纳米功能化MOFs。在此基础上，耦合自组装技术和相转变技术，将纳米功能化MOFs引入聚酰亚胺膜层结构中，并观测复合膜层结构，分析其特性，探讨纳米复合膜的形成机制。研究纳米复合膜的CO2渗透性能，分析膜层结构与性能之间的关系，并结合计算模拟，探讨复合膜内的传递机理。实现高渗透通量和高选择性，并兼顾膜稳定性的CO2优先透过MOFs-聚酰亚胺纳米复合膜的可控制备，解决高性能膜制备中的关键问题。该研究不仅在环境和气体分离方面有重大的应用价值，还可促进有机、无机、计算模拟等学科的综合交叉和有机融合，有着重要的学术意义。

气体膜分离技术具有能耗低，操作简单，几乎零排放，分离度高等优点，是实现温室气体CO2分离捕获的有效途径之一。然而，CO2分离膜的通量和选择性低的难点和问题，成为制约CO2分离膜推广应用的瓶颈。本课题中采用氨基功能化的有机配体、溶剂热和后处理集成的方法，制备了一系列氨基功能化金属有机框架纳米材料（NH2-MOFs），材料的粒径尺寸在50-70 nm。将所制备的NH2-MOFs通过各种方法掺杂到聚酰亚胺(PI)膜中，制备MOFs-聚酰亚胺复合膜。通过铸膜法制备了微米级厚度的MOFs-聚酰亚胺复合矩阵膜，得益于MOFs纳米材料在PI膜中均匀分布，以及由MOFs提供的亲CO2的氨基官能团和额外的传输通道，掺杂不同氨基化MOFs填料的复合矩阵膜的气体渗透性能均明显优于纯PI膜的性能。膜PI@NH2-MIL-101性能提升最大，CO2气体渗透率从2.17 barrer增加到5.52 barrer (增幅154.4%)。对CO2/N2分离性能从21.8增加到28.3，对CO2/CH4从18.9增加到27.1。通过热浸涂法制备了纳米级厚度的MOFs-聚酰亚胺复合管膜，该膜具有良好的H2/CO2分离性能。当MOFs负载量为20 wt%时，膜的H2/CO2分离选择性能最佳，可达为53.1，突破了Roberson上限，气体渗透通量比已报道的大多数聚合物基质膜高1-2个数量级，并且通过改变MOFs或聚合物验证了方法的可行性。