Preparation And Performance Study Of Intrinsic Microporous Polymer Gas Separation Membranes Catalyzed By Superaci

Membranes have gained an important place in gas separation technology.The vast majority of gas separation membranes used commercially are polymer based.Although widely-used,the polymeric membranes suffer from several drawbacks,such as low permeability,low selectivity,weak plasticizing resistance,easy physical aging,etc.Therefore,the development of next generation polymeric membrane materials is critically needed to solve these problems.Compared to current polymer materials,polymer of intrinsic microporous（PIMs）membranes have excellent gas separation performance and good plasticizing resistance due to their rigid-polymer chains and twisted structures.However,the preparation processes of PIMs are sometime difficult and expensive,which limited their applications in industrialized gas separation.A series of novel semi-ladder and fully-ladder type PIMs,containing9H-xanthracene units was synthesized by superacid-catalyzed Friedel-Craft polymerization.The superacid-catalyzed PIMs（SACPs）showed high molecular weight,excellent solubility and machinability.Further studies showed that the SACPs have high microporosity,amorphous chain stacking structure,high FFV and high BET specific surface area.The stiff-spirobisindane backbone could further hinder the accumulation of chain segments.As a result,the specific surface area of SACP-3＿Ph H and SACP-3＿Me could reach 568 m²/g and 540 m²/g with the total pore volume of 0.5 and 0.438,respectively.The average d-spacing showed a bimodal distribution with the peak positions at～5（?）and～8（?）.These conclusions were consistent with the simulation results obtained by MS.The pure gas permeability experiments showed that SACP-3s had superior permeability due to its fully-ladder type structure,and its separation performance of CO₂/CH₄,H₂/N₂,H₂/CH₄,O₂/N₂gas pairs were closed to the 2008 upper bound.Particularly,for CO₂/CH₄gas pair,SACP-3＿Ph H showed ultra-high CO₂permeability（6497 Barrer）with the selectivity of 7.8 and the selectivity could be further up to 13 after substituting side group to methyl.In order to investigate the plasticizing resistance of SACP-1,SACP-2 and SACP-3＿Ph H,the constant-volume/variable-pressure permeance experiment of SACP-1,SACP-2,SACP-3＿Ph H polymer membrane was carried out.The results showed that the CO₂/CH₄selectivity of SACP-3＿Ph H only decreased by 29%under the feed pressure range of 4-40 bar with the CO₂/CH₄ratio of 50/50（vol%）as feed gas,while that of PIM-1 decreased by 43%under the pressure range of 4-20 bar.The result showed that the plasticizing resistance of SACP-3＿Ph H is much better than that of PIM-1,which make it a promising candidate for natural gas decarbonization.In this thesis,a new structure of PIM materials was synthesized with excellent gas separation performance.With the merit of efficient and economical reaction process,SACP paved its way in the field of gas separation.