The Preparation And Gas Separation Properties Of MOFs/PIM-1 Mixed Matrix Membranes

In recent years,the global warming caused by the greenhouse effect has severely damaged the earth’s ecological environment,excessive emission of greenhouse gases is the primary factor leading to this hazard.Therefore,it is very important to find an efficient and environment-friendly gas separation technology for the future development of mankind.Membrane separation technology has become a hot field of current research due to its low energy consumption and simple process.The polymer of intrinsic microporous PIM-1 has extremely high free volume and high permeability,it is one of the most promising polymer membrane materials at present.By adding the nanoporous filler MOFs to the polymer matrix PIM-1 to prepare a mixed matrix membrane,the negative influence of the trade off effect can be effectively improved.In addition,the gas separation performance of the mixed matrix membrane can be improved by further modifying the MOFs material.The main contents of this paper are as follows:（1）The first part mainly studied a series of mixed matrix membranes containing MOF-801 filler.We selected PIM-1 as the polymer matrix,and successfully prepared MOF-801/PIM-1 mixed matrix membranes with different MOF-801 content by the casting method.The sample membrane was systematically characterized by SEM,XRD,TGA and FTIR,and the CO₂,O₂ and N₂permeability of the sample membrane was tested.The experimental results show that the uniform dispersion of nano-porous material MOF-801in polymer matrix provides a fast passage for gas molecules,and MOF-801 has a good affinity for CO₂,which is conducive to improving CO₂/N₂ selectivity.When the MOF-801loading was 5%,the CO₂ permeability and CO₂/N₂ selectivity of the MMMs increase synergistically.Compared with the pure PIM-1 membrane,it increases by 130%and 35%,which is significantly higher than that of the Robeson upper bound（2008）.After 100 days of physical aging test,the CO₂ permeability of MOF-801/PIM-5%mixed matrix membrane can be maintained above 70%,showing excellent anti-aging performance.After120 h continuous gas permeability experiment,the continuous working stability of the mixed matrix membrane was proved.（2）In the second part,we made further modifications to MOF-801.Ionic liquid[Bmim][NTf₂]has a good affinity for CO₂,but it is not suitable for direct use as a filler for mixed matrix membranes due to its liquid nature.We selected ionic liquid[Bmim][NTf₂]as the functional material and MOF-801 as the carrier,prepared IL@MOF-801nanocomposite by wet impregnation,it was used as a filler and blended with PIM-1.A series of mixed matrix membranes with different IL@MOF-801 content were prepared by casting method.The experimental results show that IL@MOF-801 has better CO₂ affinity than MOF-801,and the CO₂/N₂ selectivity of IL@MOF/PIM-1 mixed matrix membrane has been further improved,and it shows a good thermal stability and anti-aging properties.The sample membrane exhibits good gas separation performance in the field of gas separation,which provides more ideas for the research of MMMs based on PIM-1polymer.