Design And Synthesis Of Conjugated Microporous Polymers For CO₂ Capture And Separation

Conjugated microporous polymersas emerging a calss of novelorganic microporous materials have high specific surface area（reported PPN-4 up to 6461 m²/g）and low skeletal density（consisted by the light element C,N,B,H）,as well as the modifiability of the skeleton and the tunability of the pore size,and excellent thermal stability（TGA analysis generallybreak down from 350^oC or higher temperature）and good chemical stability（insoluble incommon organic solvents and strong acid or bases）,and the diversity of synthetic methods（such as Suzuki coupling,Yamamoto coupling,Sonogashira-Hagihara coupling,Glaser coupling,Lewis acid catalyzed ring trimerization,Imine reaction and the formation of boron oxide,etc.）and other excellent properties,which has wide range of applicationsin the gas adsorption,separation,catalysis and gas storage.In this paper,Sonogashira,Yamamoto,Suzuki cross-coupling reactions were used to synthesize a series of three-dimensional skeletal materials by selecting different structural elements as structural units.The effects of polymer skeleton structure,degree of branching,length of connecting unit and geometrical configuration on the specific surface area,pore volume and pore size of conjugated microporous polymer materials were systematically studied.In the first chapter,the research status and development of conjugated microporous polymers are described.It has excellent performance in gas adsorption,separation,catalysis and gas storage.We also briefly discussed the conjugation of microporous polymers and its application in human life.The second chapter mainly explains the main characterization methods and the use of experimental reagents.In the third chapter,three conjugated microporous polymer containing heteroatom S and carboxylgroups based on the 2,5-dibromo-3-carboxy-thiophene-based units were prepared via the Sonogashira-Hagihara coupling reaction.The samples were characterized by Fourier transform infrared spectroscopy（FT-IR）,¹³C solid-state NMR,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,thermogravimetric analysis（TGA）,specific surface area（BET）and carbon dioxide adsorption.The chemical composition,morphology,thermal stability,pore properties and gas storage properties of CMPs with thiophene and carboxyl functional groups were studied.We found that the polymers had high specific surface area,SCMP-COOH@1 had a specific surface area of911 m²/g and the microporous surface area of 473 m²/g,the smaller pore size（0.5-0.7nm）,and the larger carbon dioxide adsorption heat of 34 kJ/mol.Under the conditions of273 K and 1.05 bar,the amount of CO₂ adsorbed on the polymer SCMP-COOH@1 was 94mg/g,and the carbon dioxide adsorption capacity of the polymer was 812 mg/g at 318 K and 60 bar.The selectivity of CO₂/N₂of the samples was calculated by the ideal adsorption solution theory（IAST）at 273 K by simulating the flue gas group composition（nitrogen:carbon dioxide=（85:15）（v:v））,which range is 35.7-24.8.In the fourth chapter,we utilize Sonogashira-Hagihara,Suzuki and Yamamoto coupling reactions,1,3,5-tri（3,5-dibromophenyl）benzene as the basic unit reacte with a varietyofacetylenicmonomers（1,4-diethynylbenzene,1,3,5-triethynylbenzene,tetraacetylene phenylmethane,tetraacetylene styrene）,bornic acid monomer（1,4-phenylene dibornic acid,4,4-biphenyldibornic acid）to prepare a series of CMPs.The samples were characterized by Fourier transform infrared spectroscopy（FT-IR）,¹³C solid-state NMR,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,thermogravimetric analysis（TGA）,specific surface area（BET）analysis,and carbon dioxide adsorption analysis.The morphology of theCMPs was studied by chemical composition,morphology,thermal stability,pore properties and gas storage properties.It was found that the morphology of the CMPs was spherical to nanometer spherical solid,although the arrangement was disordered but had a uniform pore size.The pore size is mainly distributed between 0.46-0.70 nm and the specific surface area is 570-1150 m²/g.The adsorption capacity of methane and carbon dioxide is up to 20 cm³/g and 81cm³/g,respectively.We calculated the CO₂/N₂ selectivity by applying the ideal adsorption solution theory（IAST）at 273 K,which simulate the main gas composition of the flue（nitrogen:carbon dioxide=（85:15）（v:v））and the CO₂/N₂ selectivity is 21.2-48.9,this is ideal for applications where carbon dioxide is captured after combustion.In addition,the selectivity of CO₂/CH₄ is4.1-5.8 at a molar ratio of carbon dioxide to methane of 50:50,which is also a potential application in natural gas separation.