Construction Of Porous Aromatic Frameworks By Tr?ger’s Base Via 4-Tritylaniline And Their Gases Adsorption Properties

Porous organic frameworks（POFs）is a kind of porous polymer connected by covalent bonds of organic building blocks composed of light elements（carbon,hydrogen,oxygen,nitrogen,and boron,etc）through polymerization reaction.POFs possess the characteristics of low skeleton density,high stability,large specific surface area,diverse structure,and easy modification,and POFs have been widely studied in the fields of adsorption and separation,catalysis,and sensing,etc.For synthesis of POFs,the types of polymerization reaction and building blocks are mainly focused on.For the polymerization reactions,according to the type of catalyst,mainly include no catalyst,acid catalyst,alkali catalyst,noble metal catalyst,transition metal catalyst,Lewis acid catalyst,and other polymerization reactions.Among them,the Lewis acid catalysts are cheap and readily available,and building monomers and polymerization conditions are relatively simple.Therefore,Lewis acid-catalyzed polymerization reactions are widely used to synthesize POFs;for the building blocks,the rich varieties determine that POFs have good structural modulation and modifiability,thus new building blocks need to be continuously developed in the research of POFs.Tr?ger’s base is a diamine possessing two bridge-head N atoms.The two aromatic rings close connected the bicyclic framework are nearly perpendicular,bringing about a rigid,V-shaped configuration.Due to its unique and rigid geometry,research on POFs by tr?ger’s base has gradually increased in recent years.In this thesis,one tr?ger’s base via 4-triphenylmethaniline used as a monomer,with anhydrous iron trichloride and aluminum trichloride as catalysts,respectively,a series of PAFs（PAF=Porous Aromatic Framework）were synthesized by regulating the solvent concentration of the reaction system,and the adsorption and separation properties of their small molecular gases were studied.The specific researches are as follows:1.Construction of PAF-102s catalyzed by iron trichloride and based on tr?ger’s base of 4-tritylaniline,and their adsorption and separation properties of small hydrocarbons.A tr?ger’s base monomer was synthesized from 4-tritylaniline,with anhydrous iron trichloride as the catalyst,formaldehyde dimethyl acetal as external cross-linker,and 1,2-dichloroethane as a solvent,PAF-102s were synthesized by regulating the reaction monomer concentration and the amount of cross-linker.By comparison with IR spectra between monomer and PAF-102s,it indicates that polymerization has already occurred.Scanning electron microscopy（SEM）shows that PAF-102s are filamentous fibers with uneven thickness between 30 and 100 nm in diameter.Nitrogen adsorption-desorptions at 77 K indicate that PAF-102s are microporous materials,the BET（BET=Brunauer Emmett Teller）surface area of PAF-102-b and PAF-102-d is relatively high(648 m²g^-1and 636 m²g^-1,respectively),and the adsorption and separation properties of their small hydrocarbons are studied at273 K and 298 K.At 298 K and 1 bar,the adsorption capacity of C₂H₆,C₂H₂and C₂H₄for PAF-102-b is 38.1 cm³g^-1,46.5 cm³g^-1and 35.5 cm³g^-1,respectively;the adsorption capacity of CH₄,C₂H₆and C₃H₈for PAF-102-b is 7.9 cm³g^-1,38.1 cm³g^-1and 51.1 cm³g^-1,respectively.At 298 K and 1 bar,the adsorption capacity of C₂H₆,C₂H₂and C₂H₄for PAF-102-d is 40.3 cm³g^-1,45.3 cm³g^-1and 35.7 cm³g^-1,respectively;the adsorption capacity of CH₄,C₂H₆and C₃H₈for PAF-102-d is 7.5 cm³g^-1,40.3 cm³g^-1and 67.0 cm³g^-1,respectively.Calculated from IAST（Ideal Adsorbed Solution Theory）,at 298 K and 100 k Pa,the separation selectivity of C₂H₆/C₂H₄,C₂H₂/C₂H₄,C₃H₈/CH₄and C₂H₆/CH₄for PAF-102-b is 1.3,1.6,441.6 and 27.9.At298 K and 100 k Pa,the separation selectivity of C₂H₆/C₂H₄,C₂H₂/C₂H₄,C₃H₈/CH₄and C₂H₆/CH₄for PAF-102-d is 1.5,1.5,10590.7 and 45.5,respectively.2.Construction of PAF-103s catalyzed by aluminum trichloride and based on tr?ger’s base of 4-tritylaniline,and their adsorption and separation properties of small-molecule gases.Utilizing the tr?ger’s base monomer from 4-tritylaniline,with anhydrous aluminum trichloride as catalyst,trichloromethane as solvent,PAF-103s are synthesized by regulating the reaction monomer concentration and amount of the catalyst.By comparison with IR spectra between monomer and PAF-103s,it demonstrates that polymerization already occurs.SEM shows that PAF-103s are small spheres of approximately 300 nm in diameter.Nitrogen adsorption-desorptions indicate that PAF-103s are microporous materials.The BET surface area of PAF-103-a,PAF-103-b,and PAF-103-c is 610 m²g^-1,601 m²g^-1,and 532 m²g^-1,respectively.At 273 K and 298 K,the adsorption and separation properties of small hydrocarbons,nitrogen,and carbon dioxide are explored.At 298 K and 1 bar,the adsorption capacity of CH₄,C₂H₆,C₃H₈and CO₂for PAF-103-a is 7.6 cm³g^-1,37.3cm³g^-1,52.1 cm³g^-1and 30.3 cm³g^-1,respectively;and the adsorption capacity of CH₄,C₂H₆,C₃H₈and CO₂for PAF-103-c is 12.3 cm³g^-1,57.9 cm³g^-1,75.9 cm³g^-1and 47.2 cm³g^-1,respectively.Calculated from IAST,at 298 K and 100 k Pa,the separation selectivity of C₃H₈/CH₄,C₂H₆/CH₄,CH₄/N₂and CO₂/CH₄for PAF-103-a is332.0,27.6,5.8 and 7.0,respectively.And at 298 K and 100 k Pa,the separation selectivity of C₃H₈/CH₄,C₂H₆/CH₄,CH₄/N₂and CO₂/CH₄for PAF-103-c is 487.8,32.5,9.5 and 7.4,respectively.