高性能金属有机框架基复合矩阵膜的设计与制备研究

Membrane separation technology is an efficient way for gas separation. Metal-organic frameworks (MOF) are promising membrane materials for gas separation. However, However, the preparation of a high-quality MOFs membrane is still very challenging because the heterogeneous nucleation density of most MOFs crystal on supports is quite low. This proposal first synthesizes nano-sized MOF with controlled pore structure, crystalline size and morphology, and functionalizes the MOF with organic amines. The mechanism of controlled synthesis is studied in detail. Based on this, functionalized MOF is combined with polymer by self-assembly method using dopamine as the binding agent to prepare MOF-Polymer mixed matrix membrane. The micro-structure of MMM is characterized and the formation mechanism of MMM is discussed. On the one hand, the high adsorption capacity of amines leads to a good separation performance of MMM. On the other hand, the unique porous merit of MOF could promote the diffusion of gases inside MMM. Besides, the presence of polyamine as coupling agent is beneficial for homogeneous dispersion of MOF in the polymer matrix, reducing non separative voids. The MMM is studied in CO2 separation and relationship between membrane structure and separation performance is correlated. Combined with simulation, the adsorption and diffusion behavior of CO2 and other gases in MMM is investigated. The proposal aims to develop a controllable and reproducible way of synthesis MMM with high permeability and selectivity, simultaneously for separation of CO2/N2, CO2/CH4, CO2/H2. This project is of great importance in both academy and application.

膜分离技术是气体分离的一条有效途径，金属有机框架（MOF）是一种潜在的气体膜分离材料，然而MOF在通用支撑体上成核密度低，成膜困难。本项目从纳米MOF粉体的尺寸、形貌调控入手，采用有机胺对MOF进行功能化，探讨功能化MOF的可控制备规律；在此基础上以多巴胺为偶联剂耦合功能化MOF与聚合物，制备MOF-聚合物复合矩阵膜。观测膜结构、揭示成膜规律。一方面， MOF独特的孔结构促进气体在膜内的扩散；另一方面，胺的高CO2吸附能力增强矩阵膜的分离性能；此外，多巴胺有利于MOF在聚合物中的分散，减少缺陷。研究复合膜的CO2分离能力，分析膜结构与分离性能间的内在联系，并结合计算模拟，探讨CO2, CH4, N2, H2在膜内的吸附、扩散机理。最终实现同时具有高通量与高分离性能的膜材料的可控制备，用于CO2/N2、CO2/CH4、CO2/H2等气体混合物的分离，具有重要意义。

金属有机框架（MOF）膜在气体分离领域有具有很好的潜在应用前景。然而，MOF在通用的支撑体上成核密度低，目前MOF膜的生长还仅仅局限于ZIF-8等几种，还难以通过水热合成制备高质量、重复性好的 MOF 膜。因此，本项目研究功能化MOF材料与有机膜材料耦合，制备矩阵膜（MMM），研究了CO2吸附、膜分离性能。具体内容如下：通过大量实验探索，获得纳米MOF（如MIL-101(Cr)–NH2、ZIF-L、ZIF-8等）材料的尺寸及形貌调控规律；通过后合成共价修饰实现在MIL-101(Cr)–NH2上引入不饱和羰基基团，功能化MOF的热稳定及CO2/N2分离能力较未功能化MOF有显著提高，CO2/N2由原来的10.93增大至16.44；通过耦合自组装技术和相转化技术，利用多巴胺作为偶联剂，将功能化纳米MOF（MIL-101(Cr)–NH2）粉体与PMMA进行耦合，构建功能化MOF-聚合物混合矩阵膜。获得了膜层结构、分离性能调控规律，优化条件下制备的MMM膜与纯的PMMA膜相比，H2通量提高了3个数量级，并且保持了较高的H2/CO2分离系数（13）。此外，还拓展了ZIF-L膜材料的应用范围，以ZIF-L膜为模板合成了一系列纳米片阵列作为超级电容器的整体电极材料。电极材料表现出优异的电化学储能性能。组装的超级电容器器件的能量密度和功率密度可分别达40 Wh kg-1和850 W kg-1以上。