Bi Xiangyu, Zhang Yong'an, Zhang Feng, Zhang Shenxiang, Wang Zhenggong, Jin Jian
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China.
ACS Appl Mater Interfaces. 2020 Oct 28;12(43):49101-49110. doi: 10.1021/acsami.0c14639. Epub 2020 Oct 16.
In the mixed matrix membrane (MMM), the interface between the filler and the polymer matrix will directly affect the gas separation performance of the membranes. Reasonable interfacial design in MMMs is thus important and necessary. In this work, metal-organic coordination interaction is used to construct the interface in metal-organic framework (MOF) nanosheet-based polyimide MMMs where ultrathin Co-benzenedicarboxylate MOF nanosheets (CBMNs) with a thickness less than 5 nm and a lateral size more than 5 μm are synthesized as fillers and a carboxyl-functionalized polyimide (6FDA-durene-DABA) is used as a polymer matrix. Because of the high aspect ratio (>1000) of CBMNs, abundant metal-organic coordination bonds are formed between Co in CBMNs and the -COOH group in 6FDA-durene-DABA. As a result, the 6FDA-durene-DABA/CBMN MMMs exhibit improved separation performance for the CO/CH and H/CH gas pairs with H/CH and CO/CH selectivities up to 42.0 ± 4.0 and 33.6 ± 3.0, respectively. The enhanced interfacial interaction leads to the comprehensive separation performance of CO/CH and H/CH gas pairs approaching or surpassing the 2008 Robeson upper bound. In addition, the CO plasticization pressure of the MMMs is significantly enhanced up to ∼20 bar, which is 2 times that of the pure 6FDA-durene-DABA membrane. When separating a mixed gas of CO/CH, the selectivity of CO/CH remains stable at around 23 and the CO permeability keeps around 400 barrer during the long-term test.
在混合基质膜（MMM）中，填料与聚合物基体之间的界面会直接影响膜的气体分离性能。因此，在MMM中进行合理的界面设计至关重要且必要。在这项工作中，利用金属-有机配位相互作用在基于金属-有机框架（MOF）纳米片的聚酰亚胺MMM中构建界面，其中合成了厚度小于5 nm且横向尺寸大于5 μm的超薄钴苯二甲酸酯MOF纳米片（CBMNs）作为填料，并使用羧基官能化聚酰亚胺（6FDA-均苯四甲酸二酐-二氨基联苯醚）作为聚合物基体。由于CBMNs的高长径比（>1000），CBMNs中的钴与6FDA-均苯四甲酸二酐-二氨基联苯醚中的-COOH基团之间形成了丰富的金属-有机配位键。结果，6FDA-均苯四甲酸二酐-二氨基联苯醚/CBMN MMMs对CO/CH4和H2/CH4气体对表现出改善的分离性能，H2/CH4和CO/CH4选择性分别高达42.0±4.0和33.6±3.0。增强的界面相互作用导致CO/CH4和H2/CH4气体对的综合分离性能接近或超过2008年的罗伯逊上限。此外，MMMs的CO增塑压力显著提高至约20 bar，是纯6FDA-均苯四甲酸二酐-二氨基联苯醚膜的2倍。在分离CO/CH4混合气体时，CO/CH4的选择性在长期测试中保持在23左右稳定，CO渗透率保持在400巴耳左右。
