Preparation And Performance Of Gas Separation Membrane Based On COF-5

Excessive CO₂ emission derived from population expansion and industrial development is the main reason for the Greenhouse Effect,which is one of the greatest global issues currently confronting us.Thus,the capture and storage of CO₂is well concerned and the key to sustainable development.The separation based membrane has the advantage of efficiency,green and energy saving,which is recognized as an effective method for the selective removal of CO₂ to other technologies.At present,mixed matrix membranes combined the advantages of polymer membranes and inorganic membranes have been widely applied to gas separation.Covalent organic frameworks?COFs?represent a type of promising porous crystalline material with high surface area and unique pore structure,they have enormous potential application in adsorption,energy storage,catalysis,chemo-sensing and medicine,especially in gas storage fields.In this paper,we prepared two types of mixed matrix membranes based on COF material,and further applied to CO₂/N₂ separation system.The main contents are as follows:?1?In this work,the COF-5 nanosheet was synthesized via a facilely sonochemical method,which shows the high CO₂ uptake capacities because of its unique structure.Then,COF-5 was dispersed in Pebax-1657 matrix to fabricate the mixed matrix membranes?MMMs?.The high-porosity structure of COF-5 combined with matrix promoted gas permeation collectively and the resulting MMMs exhibits an enhanced CO₂ permeability.Remarkably,the MMM that consists of 0.4 wt%COF-5 filler showed the highest CO₂ permeability??493 Barrer?.Furthermore,compared with the pristine Pebax-1657 membrane,the COF-5/Pebax membrane improved the CO₂/N₂ selectivity?from 31.3 to 49.3?.It is worth mentioning that all the MMMs showed good stability.?2?Here,we introduced COF-5 material into the new polymer PIM-1 to prepare COF-5/PIM-1 membranes.Owing to good compatibility between COF-5 and PIM-1matrix,the resulting membranes showed uniform structure with few defects,and achieved enhanced CO2 permeability without reducing the CO2/N2 selectivity.The prepared MMM?0.5 wt%?showed an increment of 4 fold in CO₂ permeability compared with pure PIM-1 membrane.In summary,this strategy has successfully applied boric acid COF to gas separation membrane,which provides a reference for the future research.