Structure Control And Performance Study Of Gas Separation Membrane Based On Self-organizing Microporous Polymer

With the rapid development of social economy,human activities have caused the continuous deterioration of the natural environment,and the development of cost-effective CO₂ separation and capture technology has gradually given widespread advertence in the world.Contrast with traditional CO₂ separation and capture technology,CO₂ gas separation membrane,as a new industrial technology,has the characteristics of low energy consumption,high efficiency,simple operation and environmental friendliness.At present,the production demand in the domain of industrial gas separation is quickly increasing.Traditional gas separation membrane materials cannot meet the actual needs.Therefore,it is particularly important to study gas separation membranes with high permeability and high selectivity.In this report,the Polymers of intrinsic microporosity(PIM-1)was taken as the polymer matrix material,PIM-1 is a novel class of polymeric microporous materials with high permeability and modest selectivity,due to the rigid and contorted molecular structure in PIMs which disturbs the ordered packing of polymer chains.Because of its relatively low selectivity which cannot cater the actual requirements of industrial production,it's of enormous necessary for gas separation membrane applications to the design and develop high-production PIMs membranes.This report is based on the microstructure regulation of PIMs and study their gas separation performance,which are separated into the successive three parts:(1)Preparation of PIM-Br/PBI blending and crosslinking with heating membranes.The as-prepare membranes was characterized by TGA,XRD,XPS and SEM.The discussions illustrated that the crosslinking interaction of the imidazoles of PBI and-C-Br groups in PIM-Br,and thermal self-crosslinking of PIM-Br.With the increasing of PBI content,the gas permeability of the PIM-Br/PBI membranes was decreased,but the selectivity was imporved.Meanwhile,the gas permeabilities of thermally treated membranes increased with increasing the heating temperature compared with the PIM-Br/PBI-95:5 membrane which was attributed to formation of a larger free volume,and the stable cross-linking structure.The results confirmed by TGA,XRD and XPS showed that with the increase of thermal treatment,the polymer chains distance increased gradually,which was good for the gas permeability improvement.Thus,the highest CO₂ permeability could be achieved to be 3313.69 Barrer for PIM-Br/PBI-95:5-300 membrane which had ideal permselectivity of CO₂/CH₄ of 12.7.Subsequently,the plasticization by CO₂ and mechanical properties were further tested,and the results indicated the excellent anti-plasticization ability and mechanical properties of crosslinking membranes.(2)Modification of PIM-1 by hydrazine hydrate which converts-CN of PIM-1 into hydrazone.The chemical structure and microporous structure were characterized by FT-IR and BET.With the increase of hydrazine hydrate in reaction,the gas permeabilities of H-PIM-1 was decreased with the significantly increases selectivity.Among them,H-PIM-1-30ml shows the best gas separation performance,with the higher CO₂ permeability(1758.63 Barrer)and the highest ideal selectivity of CO₂/N₂(23.9)and CO₂/CH₄(18.6).In addition,the result of mixed gas separation performance showed that H-PIM-1 demonstrated higher CO₂/CH₄ selectivity of 32.3 and CO₂permeability of 1483 Barrer for mixed gas CO₂/CH₄ and higher CO₂/N₂ selectivity of34 and CO₂ permeability of 1466.4 Barrer for mixed gas CO₂/N₂.At the same time,the separation performances of mixed-gas CO₂/CH₄ of H-PIM-1membrane exceed the mixed-gas 2018 Robeson upper bound.