In this study, a novel scheme to fabricate nano-composite membrane materials containing fully dispersed nano-size zeolitic imidazolate frameworks (ZIFs) has been proposed for the first time. By mixing the as-synthesized ZIF-7 nano-particles without the traditional drying process with polybenzimidazole (PBI), the resultant membranes not only achieve an unprecedented ZIF-7 loading as high as 50 wt%, but also overcome the low permeability nature of PBI. The membranes exhibit characteristics of high transparency and mechanical flexibility, together with enhanced H 2 permeability and ideal H 2 /CO 2 permselectivity surpassing both neat PBI and ZIF-7 membranes. Advanced instrument analyses have confirmed the unique ZIF-polymer interface and elucidated the mixed matrix structure that contributes to the high ZIF loading and enhanced gas separation performance superior to the prediction from the Maxwell model. The high thermal stability, good dispersion of ZIF nanoparticles with minimal agglomeration and the attractive gas separation performance at elevated temperatures up to 180 C indicate the practicability of this nano-composite material for hydrogen production and CO 2 capture in realistic industrial applications under harsh and extreme environments.

High‐performance zeolitic imidazolate frameworks (ZIFs)/polybenzimidazole (PBI) nanocomposites are molecularly designed for hydrogen separation at high temperatures, and demonstrate it in a useful configuration as dual‐layer hollow fibers for the first time. By incorporating as‐synthesized nanoporous ZIF‐8 nanoparticles into the high thermal stability but extremely low permeability polybenzimidazole (PBI), the resultant mixed matrix membranes show an impressive enhancement in H2 permeability as high as a hundred times without any significant deduction in H2/CO2 selectivity. The 30/70 ZIF‐8/PBI dense membrane has a H2 permeability of 105.4 Barrer and a H2/CO2 selectivity of 12.3. This performance is far superior to ZIF‐7/PBI membranes and is the best ever reported data for H2‐selective polymeric materials in the literature. Meanwhile, defect‐free ZIF‐8‐PBI/Matrimid dual‐layer hollow fibers are successfully fabricated, without post‐annealing and coating, by optimizing ZIF‐8 nanoparticle loadings, spinning conditions, and solvent‐exchange procedures. Two types of hollow fibers targeted at either high H2/CO2 selectivity or high H2 permeance are developed: i) PZM10‐I B fibers with a medium H2 permeance of 64.5 GPU (2.16 ×10−8 mol m−2 s−1 Pa−1) at 180°C and a high H2/CO2 selectivity of 12.3, and, ii) PZM33‐I B fibers with a high H2 permeance of 202 GPU (6.77 ×10−8 mol m−2 s−1 Pa−1) at 180°C and a medium H2/CO2 selectivity of 7.7. This work not only molecularly designs novel nanocomposite materials for harsh industrial applications, such as syngas and hydrogen production, but also, for the first time, synergistically combines the strengths of both ZIF‐8 and PBI for energy‐related applications.

Nanocrystals of ZIF-90 have been synthesized at room temperature through a novel procedure and incorporated into PBI-based nano-composite membranes for hydrogen purification. The physical and chemical structures of the ZIF-90 nanoparticles have been examined via multiple advanced instrumental analyses including DLS, XRD, FESEM, NMR and FTIR. The nanocrystals show identical morphology, crystallinity and chemical structure but a significantly reduced particle size (around 100 nm) when compared with the ZIF-90 particles in previous studies. The derived ZIF-90-PBI nano-composite membranes exhibit homogeneous particle dispersion and fine particle-polymer adhesion, as well as excellent hydrogen purification performance at various testing conditions. The 45/55 (w/w) ZIF-90-PBI membrane with the highest ZIF-90 volume loading of up to 50.9 vol% possesses the best ideal H 2-CO 2 separation performance with a moderate H 2 permeability of 24.5 Barrer and a high H 2-CO 2 selectivity of 25.0 in pure gas permeation tests at 35 C. The membrane also shows promoted gas separation performance during mixed gas tests at 180 C with an H 2 permeability of 226.9 Barrer and an H 2-CO 2 separation factor of 13.3 that surpasses the latest Robeson upper bound for H 2-CO 2 separation. This work not only expands the field of nano-composite membrane fabrication, but also provides prospects for interdisciplinary research combining nano-science and chemical engineering for clean energy development.

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