| The metal-organic frameworks（MOF）composed of organic ligands and metal centers have the characteristics of diverse structures,huge specific surface area,excellent adsorption performance,and regular pores.These characteristics make it have the great research and application value in gas separation.There are endless researches on MOF film formation,However,most of the current preparation methods of MOF membranes are complicated,time-comsuming and high required of conditions,which is difficult to used in large-scale production of MOF membranes.We have proposed a method that can quickly prepare high-performance MOF films under normal temperature and pressure,called Fast-Current-Driven Synthesis（FCDS）.The supporting substrate used in this method is highly ordered sheet-like porous anodic aluminum oxide（Anodic Aluminum oxide,AAO）.Because AAO itself does not have conductivity,it needs to be coated with a layer of Pt by magnetron sputtering,which is expensive.In addition,the packing density of the planar membrane is small,resulting in a small effective filtration area per unit volume and low separation efficiency.At present,the membrane separation module commonly used in the industry is the hollow fiber membrane module.Its high packing density provides a high specific surface area（9000 m2/m3）,which is much higher than planar membranes and tubular membranes（30～500 m2/m3）.To solve the above problems,this paper first selects ceramic hollow fiber,which packing density is great high.To increase the surface conductivity,we coated graphite on the surface.Than we used FCDS to prepare a series of ZIF-8@ceramic hollow fiber membranes in situ.Afterwards,conductive stainless steel hollow fiber was used as the supporting substrate,and a series of ZIF-8@stainless steel hollow fiber membranes were prepared in situ by FCDS.Finally,the microstructure and gas separation performance of the above ZIF-8@hollow fiber membranes are studied.The specific research contents are as follows:（1）A layer of 2μm graphite was coated on the surface of the ceramic hollow fiber by scraping to make the surface of the insulation substrate conductive.Afterwards,the modified ceramic hollow fiber is used as the substrate,and a series of ZIF-8@ceramic hollow fiber membranes with different current densities and different growth times are generated on the surface by the FCDS.When the current density is 0.74 m A/cm2,its C3H6/C3H8 separation factor is 63.Through the refined analysis of its phase structure,it can be seen that the rigid ZIF-8＿Cm phase content in the membrane at this time is as high as 71%,and its inhibited ligand rotation makes its pore size just between the dynamic diameters of C3H6 and C3H8.This is also the reason why it can achieve efficient separation of C3H6/C3H8 with precise pore size screening.In addition,the film has good pressure resistance and long-term operation stability.（2）Using the PDA-modified stainless steel hollow fiber as the substrate,a series of ZIF-8@stainless steel hollow fiber membranes with different current densities are generated on the surface by the fast current drive method.We found that when the current density is 0.76 m A/cm2,its H2/CO2 separation coefficient is 14,which is higher than the corresponding Knudsen diffusion coefficient of 4.69.The refined analysis of its phase structure shows that the rigid triclinic phase（R3m）content in the membrane reaches 59%.The smaller theoretical pore size of this phase is 3.1?and the inhibited ligand rotatability make it just to achieve high efficiency separation of H2（2.9?）and CO2（3.3?）.In addition,the film has good continuous temperature change and long-term operation stability. |
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