Abstract:

Metal-organic framework (MOF), which has the advantages of high specific surface area, abundant porosity and adjustable pore size, has received attention from many scholars and is considered as an ideal adsorbent for adsorption and separation. However, in practical applications, most microporous MOF materials are severely limited in their intrinsic mass transfer rates during adsorption, and methods for constructing hierarchically pores are not universally applicable. In this paper, the methods for constructing hierarchical pores MOF such as moderator strategy, template strategy and post-processing strategy were introduced. The hierarchically pores materials with both mesopores and macropores were prepared, and the advantages and disadvantages of each method with application scenarios to obtain a universal strategy for constructing hierarchical pores MOF with adjustable pore size under relatively mild conditions were evaluated. To address the application of hierarchically porous MOF materials in the field of gas adsorption and separation, this paper focused on the case of constructing hierarchical pores MOF to enhance the adsorption of CO₂ gas. It was found that the construction of hierarchically porous increased the pore size, improved the specific surface area of MOF, and provided additional pore channels to enhance the adsorption capacity and mass transfer rate of gas molecules. The results showed that the hierarchically pores MOF had excellent performance in gas adsorption and separation. Finally, the problems of hierarchical pores MOF synthesis and application were discussed, and the challenges faced by hierarchical pores MOF such as green reproducibility of the synthesis process were prospected.

Key words: metal-organic framework, hierarchically pores, gas adsorption, separation, mass transfer rate

摘要：

金属有机框架材料（MOF）因其具有高比表面积、丰富孔隙率、孔径可调的优点，受诸多学者关注，被认为是用于吸附分离的理想吸附剂。但是在实际应用中，大部分微孔MOF材料在吸附过程中的内在传质速率严重受限，而且构建多级孔的方法一般不具有普遍性。本文介绍了调节剂策略、模板策略、后处理策略等构建多级孔MOF的方法，制备了兼具介孔、大孔的多级孔材料，并结合应用场景评价各方法的优缺点，以获得在相对温和条件下构建孔径可调的多级孔MOF的普适性策略。针对多级孔MOF材料在气体吸附分离领域的应用问题，着重剖析了构建多级孔MOF对CO₂气体吸附提升的案例，发现多级孔的构建增加了孔径，提高了MOF的比表面积，提供了额外的孔通道，使气体分子的吸附容量和传质速率得到提升，表明多级孔MOF在气体吸附分离方面有优异的性能。最后讨论了多级孔MOF合成和应用存在的问题，并对多级孔MOF面临的合成过程绿色可重复等挑战进行了展望。

关键词: MOF材料, 多级孔, 气体吸附, 分离, 传质速率