Preparation And Modification Research Of Naphthol Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbon（PAHs）is derived from the hybridization of SP² carbon atoms,and adjacent benzene rings form planarπ-conjugated systems by sharing two carbon atoms.PAHs as the structural unit of high-performance carbon materials（such as carbon nanotubes,graphene,heat-conducting graphite,graphene carbon fibers,graphene nanoribbons,etc.）has gained attractive attention.By studying the synthesis process and reaction mechanism,the structure and properties of PAHs can be regulated,and the best precursor of different high performance carbon materials also can be obtained.Naphthalene was used as raw material to synthesize PAHs.The synthesis process and reaction mechanism,the correlation of structure and properties of resulted PAHs,the process and properties of carbon materials prepared by PAHs as precursor were explored.The main research contents of this thesis are as follows:1.The PAHs was prepared by Scholl reaction with using naphthalene as raw material,dichloromethane as solvent and solid Lewis acid as catalyst.The influences of synthesis temperature,catalyst type and adding method,molten salt and other factors on the structure and properties of PAHs were investigated,and the synthesis mechanism of PAHs was also explored.Researches showed that when the synthesis temperature was 60℃in the system of Al Cl₃/Fe Cl₃,the prepared PAHs was mainly naphthalene tetramers.When the temperature increased to150℃～250℃,the components were more complex,and the main naphthalene trimers,tetramers,pentamers and their derivatives were synthesized.When the temperature increased rapidly to 400℃,due to the sublimation of Al Cl₃ in the system,the violent reaction of the PAHs was avoided and the molecular structure of PAHs-400℃was basically consistent with that of PAHs-60℃.In addition,the prepared PAHs in Fe Cl₃ system were naphthalene oligomers with definite structure.There were mainly naphthalene tetramers,pentamers,hexamers and heptamers,in which the contents of naphthalene tetramers and pentamers were higher,and the contents of hexamers and heptamers were lower.By comparing the two systems,it could be found that in addition to the polymerization reaction of naphthalene,the former reaction system also contained the Friedel-Crafts reaction of naphthalene and solvent,and the reaction mechanism of the latter was mainly the cationic polymerization reaction of naphthalene.2.Nano-graphene molecule with good dispersion was obtained by co-carbonization of molten salt and prepared PAHs.The thickness of nano-graphene molecule was about 2 nm,and the transverse size was in the range of 50～60 nm.In addition,the prepared nanographene molecule had semiconductor properties and its Hall effect test results at 298.15 K were as follows:resistivity was 5.58×10³?/cm,Hall coefficient was1.28×10⁸cm³/C,carrier density was 4.88×10¹⁰cm^-3 and Hall mobility was219 cm²/V·s.Its optical band gap was about 5.45 e V by ultraviolet absorption spectrum test and it was a new kind of wide band gap semiconductor.Its photoluminescence spectrum had a high intensity peak at 394 nm,which showed excellent photoluminescence characteristics.Its infrared emissivity in 2.5～25μm was in the range of 94%～97.5%and it exhibited excellent heat dissipation performance.3.Hypercross-linked porous organic polymer material with a specific surface area of 786.13 m²·g^-1 and high proportion ultramicropores in 0.58 nm.The sample after carbonization at 800 C still possessed a specific surface area of 710.00 m²·g^-1 and showed a monodisperse pore structure with a pore size of only 0.4 nm,and its CO₂uptake increased to 3.81 mmol·g^-1 at 273.15 K/1.0 bar and H₂ uptake was up to 7.00 mmol·g^-1 at 77.3 K/1.0 bar.Porous carbon materials with multi-level pore structure were prepared with using resulted PAHs as precursor and nano-Si O₂ as hard template.AC-Si O₂-5K-700 had a specific surface area of 3283.89 m2·g^-1and micropore volume of 1.92m³·g^-1.The electrochemical capacity was compared among carbonized hypercross-linked porous organic polymer material,porous carbon materials with hard template and self-made asphalt based activated carbon.Carbonized crosslinked polymer has the worst capacitance performance,and porous carbon material prepared by hard template method has the highest capacitance of large current ratio among the three.4.Two kinds of polycyclic aromatic hydrocarbon based fibers were prepared by melt spinning after alkylation of polynaphthalene by adding p-benzaldehyde and o-xylene,respectively.When the alkylation reagent was terephthalaldehyde,the softening point of the spinning raw material was 70℃,and the alkylated polycyclic aromatic carbon fiber with a average diameter of 11.10μm,average tensile strength and modulus of41.19 GPa and 840.18 MPa were prepared by spinning,oxidative dehydrogenation and carbonization.The polycyclic aromatic compound was obtained by alkylation with adding xylene and its softening point was230℃.The ultramicroporous carbon fiber with a specific surface area of410.00 m2·g^-1 and a pore size of 0.42 nm was synthesized by melt spinning,cyclization dehydrogenation,hypercross-linking and carbonization.The resulted monodispersive ultramicroporous carbon fiber showed an average diameter of 15.60μm and an average strength of797.76 MPa.Its CO₂adsorption capacity reached 3.25 mmol·g^-1 at 273.15K/1.0 bar and H₂adsorption capacity at 77.3 K/1.0 bar and 77.3 K/10 bar was 5.45 mmol·g^-1,8.6 mmol·g^-1,respectively.