Gao Zhuangzhuang,Li Baoju,Ou Shuxian,Li Dongsheng,Fang Qianrong,Qiu Shilun,Xue Ming
M etal-organic frameworks (MOFs) are attractive in membrane separation due to their special pore structure and suitable aperture size. The fabrication of defect-free and robust MOF membranes with excellent durability is highly demanded but remains challenging. In this work, we report a one-step active γ -alumina conversion strategy for the facile and reliable fabrication of an MIL-96 membrane. In this case, the γ -Al 2 O 3 sol was dip-coated and sintered on the α -Al 2 O 3 disc as the active aluminum source and substrate for the nucleation and growth of MOF. A continuous and well-intergrown MIL-96 membrane was generated with exceptional stability due to the strong adhesion to the substrate. The resultant MIL-96 membrane yielded a satisfactory H 2 /CO 2 permselectivity and high-temperature resistance, delivering a selectivity of 12.35 with H 2 permeance of 6.20×10 −7 mol·m −2 ·s −1 ·Pa −1 at 150 °C. Moreover, the probe membrane presented remarkable durability and recyclability under harsh hydrothermal conditions. This method paves the way for constructing highly stable and selective MOF membranes and could accelerate the development of advanced membrane separation technologies for gas purification and recycling in addressing the severe energy and environmental problems.
Yumeng Zhao,Guoshu Gao,Peng Zhu,Cun Liu,Xiongfu Zhang,Feichao Wu,Guohui Yang
Metal-organic framework (MOF) membranes hold great potential for acetic acid dehydration by pervaporation. However, it remains challenging to develop stable MOF membranes suitable for this application due to the corrosion of membranes by acetic acid. Herein, we report a robust aluminum (Al)-based MIL-96 membrane on porous ceramic tubes for acetic acid pervaporation dehydration. It is prepared by an induction strategy with Al-Sol@MIL-96-C layer, obtained by calcining an Al-based sol layer containing small MIL-96 seeds. The induced layer possesses a sponge-like structure and high reactivity, favoring the uniform growth of MIL-96 crystals and establishing a strong connection between the membrane layer and the support. The achieved MIL-96 membrane, with a thickness of ∼2 μm, exhibits excellent performance in separating 90 wt% acetic acid/water mixtures by pervaporation, showing a high separation factor of ∼3000 with a permeation flux of 1.54 kg/(m 2 ·h). Notably, due to the connectivity of the Al-Sol@MIL-96-C layer, these membranes show long-term operational stability for over 200 h, as well as great tolerance to ultrasonic treatment, highlighting the enormous potential for applications. This work provides a feasible approach to fabricate robust MOF membranes for pervaporation separation of acetic acid/water mixtures.
A novel approach was developed to fabricate defect-free MIL-96 membranes on an α-Al 2 O 3 support by combining aluminum isopropoxide coating with mixed-solvent regulation. The aluminum isopropoxide gel on the support functions as an active Al source, directing MIL-96 crystal nucleation and growth. A subsequent secondary crystallization can produce a well-intergrown MIL-96 membrane. Here, the gel coating inhibits the preferential crystallization of MIL-96 particles in the support pores, optimizing the microstructure and diminishing inter-crystal defects. By accurately adjusting the formic acid to N-methylformamide ratio in synthesis solution, a balance between membrane crystallinity and formation is achieved. Membrane separation property evaluation revealed an outstanding H 2 permeance of 1800 GPU and an H 2 /CO 2 separation factor of over 24.0, outperforming some advanced polycrystalline MOF membranes. This approach provides a potentially cost-efficient method for the large-scale preparation of MIL-96 membranes, holding great potential for practical applications in membrane separation.
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