Abstract:

Gas membrane separation technology is extremely common in the chemical industry. Compared with traditional gas separation technology, it has advantages such as a small footprint, low energy consumption, simple operation, energy conservation and environmental protection, and thus has a wide range of application prospects. Membrane materials, as the core of gas membrane separation technology, have been widely studied. Among them, the mixed matrix membranes (MMM) based on metal-organic frameworks (MOF) have high permeability and selectivity, making them a promising gas separation membrane material. There are various types of MOF materials with adjustable pore structure and surface modifiability. However, there are differences in properties between MOF particles and polymers, poor compatibility and uneven dispersion, leading to interface defects such as particle aggregation, polymer chain segment stiffness and particle pore blockage in MMM, which in turn affect the gas separation performance and mechanical properties of the membrane. This article summarized four methods to improve the compatibility of MOF-based MMM based on different modification principles, namely functionalization of MOF, encapsulation of MOF, modification of polymer and post-treatment of MMM. Based on the examples of researchers, the types of polymers and MOF used in the preparation of MMM, the target gas, the mechanism of modification methods and the modification objectives were explained. Comparing the permeability, selectivity and mechanical properties of MMM before and after modification, the separation effect achieved after interface modification was demonstrated. Finally, the existing modification methods were discussed and the development space for existing interface optimization methods was proposed, such as considering the characteristics of the molecules themselves, temperature and aging conditions, and using predictive models to pre-screen polymer filler combinations. In the future, it should be focused on the industrial application scenarios of MMM to increase the load capacity, maximize the advantages of porous MOF, enhance the mechanical and aging resistance of membranes, and promote the further commercial development of MMM.

Key words: mixed matrix membrane, gas separation, interface modification, metal-organic frame materials

摘要：

气体膜分离技术在化工行业中极为常见，与传统气体分离技术相比，具有占地小、能耗低、操作简单和节能环保等优点，应用前景广泛。膜材料作为气体膜分离技术的核心，被广泛研究，其中基于金属有机框架（MOF）材料的混合基质膜（MMM）兼具高渗透性和高选择性，是有潜力的气体分离膜材料。MOF材料种类繁多，具有孔道结构可调性和表面可修饰性，但MOF颗粒与聚合物存在性质差异，相容性较差，易分散不均匀，导致MMM中存在颗粒团聚、聚合物链段僵化和颗粒孔道堵塞等界面缺陷，进而影响膜的气体分离性能和机械性能。本文根据改性方法原理的不同，归纳了改善MOF基MMM相容性的四种方法，分别是MOF的改性、MOF表面修饰、聚合物的改性和MMM的后处理。结合研究者们的实例，阐述其制备MMM的聚合物种类、MOF种类、目标气体、改性方法的机理和改性目的，并通过对改性前后MMM的渗透率、选择性和机械性能进行数据对比，体现界面改性后达到的分离效果。最后，对目前存在的改性方法进行探讨，提出现有界面优化方法的发展空间，比如对分子本身特性、温度、老化条件的考虑，以及利用预测模型来预筛选聚合物-填料组合。未来，应重点关注MMM的工业应用场景，提升负载量，最大化多孔MOF的优势，增强膜的机械性能和耐老化性能，促进MMM进一步商业化发展。

关键词: 混合基质膜, 气体分离, 界面改性, 金属有机框架材料