Synthesis Of Ionic Liquild Polymer And Its Application In CO₂ Resource Utilization

Extensive research has been made on the utilization of carbon dioxide?CO₂?to make it a better value-added chemical.The cycloaddition reaction of CO₂ and epoxide to generate the corresponding cyclic carbonate is the focus of this study.Because there is no by-product in the CO₂ cycloaddition reaction,it is in line with the concept of 100%atomic utilization rate,and also conforms to the idea of contemporary“green chemistry”.At the same time,cyclic carbonates are also widely used for supercritical extraction agents,pharmaceutical intermediates,precursors of high molecular polymers,etc.Considering that the homogeneous catalyst used for the CO₂ cycloaddition reaction has limited industrial prospects,it faces problems such as subsequent separation difficulties.In this paper,a series of researches on heterogeneous catalysts for CO₂ cycloaddition are carried out with ionic liquids?ILs?as the platform.The aim is to synthesize a batch of metal-free catalysts with high catalytic activity and stable properties.First,from the perspective of accelerating the rate of material and energy transfer in the catalytic process,it is desirable to synthesize a batch of mesoporous-macroporous ionic liquid polymers?PILs?.We designed and synthesized a bisimidazolium IL with a long chain structure in the middle,ethyl ether bis?1-vinylimidazolium?chloride?[EEBVIM]Cl₂?.Then,this flexible IL with a long chain structure was polymerized with ethylene glycol dimethacrylate?EGDMA?,which also has a long chain structure,to form a large channel flexible PIL.By adjusting the molar ratio between[EEBVIM]Cl₂ and EGDMA in the flexible PILs,the structure and morphological changes of the flexible PILs were studied.Due to their mesoporous-macropore structure and a large number of uniformly distributed active sites,they show higher catalytic efficiency and accelerated mass transfer rate.Under mild conditions?120°C,1MPa?,without any solvents and cocatalysts,CO₂ and epichlorohydrin can be completely converted into the corresponding cyclic carbonates within 12 hours,with a selectivity of 99.9%.Under six cycles of experimental tests,the activity of the flexible PILs was not significantly lost.Next,from the perspective of the integration of CO₂ adsorption and conversion,it is hoped to synthesize a batch of PILs with a large number of microporous-mesoporous structures,and also have the activity of CO₂ cycloaddition reactions.We designed and synthesized a batch of ILs with special functional group phenyl,3-butyl-2-phenylimidazolium bromide?[C4PhIm]Br?with one benzene ring,3-benzyl-2-phenylimidazolium chloride?[BZPhIm]Cl?with two benzene ring and[BZDPhIm]Cl₂containing four benzene rings.A batch of IL-based hypercrosslinked polymers were synthesized by Friedel crafts alkylation between these ILs and crosslinkers FDA,DCX.A variety of characterization methods,such as CHN elemental analysis,XPS,nitrogen adsorption and desorption,and CO₂ adsorption tests have proved its rich microporous structure and uniformly distributed active sites.The obtained IL-based hypercrosslinked polymers not only have a good effect on the capture of carbon dioxide and the selective absorption of CO₂/N₂,but also have a high activity on the cycloaddition reaction of CO₂and epoxide without solvent,catalyst and any additives.Even under mild conditions?0.1MPa,80°C?,it exhibits high catalytic activity.With the increase of reaction time,the inert epoxide 1,2-epoxydodecane can be effectively converted under 1 bar.After five cycles,its activity has not changed.In general,two kinds of catalysts with high activity for the CO₂ cycloaddition under mild conditions have been developed in this paper.At the same time,it provides a method for the synthesis of PILs with microporous and large surface area.The relationships among surface area,pore size,active sites and catalytic effect were explored.