Zeolite imidazolate framework composite membranes prepared on amine/tannic acid cross-linked polymeric hollow fiber substrates for enhanced gas separation

In this work, a continuous dense zeolite imidazolate framework (ZIF) composite membranes for enhanced gas separation were successfully prepared on diethylenetriamine (DETA) and tannic acid (TA) cross-linked polymeric hollow fiber substrates via the in-situ solvothermal method for the first time. With strong reactivity and small molecular volume, DETA connected various TA molecules and anchored TA molecules on the organic hollow fiber substrate to form a relatively tight spatial network. The modified polyvinylidene fluoride(PVDF) support contained abundant phenolic hydroxyl, carbonyl, and amine groups, providing a large number of active sites for heterogeneous nucleation and promoting the forming of continuous and non-defect MOF film. The synergistic effect between TA and DETA not only enhanced the stiffness and durability of the MOF composite membrane, but also improved the performance of membrane on gas separation. The morphology of the amine/TA modified to support and the MOFs composite membrane was analyzed by SEM, XRD, FTIR, XPS, etc. The fabricated TA-DETA-PVDF/ZIF-8 composite membrane with a continuously dense layer and unique structural stability displayed excellent H2 permeance of 1.01 × 10-7 mol·m−2 s−1 Pa−1 and competitive H2/N2 and H2/CH4 selectivity of 24.0 and 24.4, respectively.