| Using benzoyl chloride (BC) as a modifier, coal tar pitch (CTP) was modified. Its quinoline, toluene insolubles, coking value and the changes of other physical and chemical properties were studied. The differences of modified coal tar pitch (MCTP) which obtained by different conditions were analyzed. The microstructure of the MCTP semi-coke was studied. The possible reaction mechanism was proposed; The effect of co-carbonization both of the CTP and dioctyl phthalate (DOP) on the structure of semi-coke was investigated. The thermal behavior of the co-carbonization was discussed. The microstructure of semi-coke was studied by using polarizing microscope, electronic scanner, X-ray diffractometer. The electrochemical performances of semi-coke were analysed. Finally, the effect of electric field on the structure of semi-coke was investigated by adding different electric field intensity during carbonization. And then the structure of semi-coke obtained by adding different electric field intensity during carbonization was investigated using polarizing microscope, X-ray diffractometer. At the same time, the possible reaction mechanism was proposed. Experimental studies have shown that the ordered and fibrous structures of semi-coke were an important prerequisite and guarantee for the preparation of high-quality needle coke. Therefore this paper mainly studied the property of semi-coke.Through elemental analysis for MCTP, the experiments found that the hydrogen content of CTP declined, the carbon content increased, the ratio of H/C decreased after the modification, which indicated that the polymerization have took place among CTP molecules. At the same time, a certain amount of chlorine in MCTP was found, which provides more reactive sites for the further polymerization among aromatic ring. Experimental tests showed that the value of a resin, β resin, y resin increased which showed that the degree of polymerization increased after modification. The coking value has also increased, indicating that the carbon yield increased. Through analyzing the structure of semi-coke obtained by MCTP, the result shown that the surface structure of fibrous tissue increased, and the compactness of the structure for semi-coke increased. The distance between the crystals surface (d002) decreased, the degree of order aromatic ring intergranular distance increased. It indicated that the modification was propitious to increase the degree of graphitization.After analyzing the thermal behavior of co-carbonization, the experiment showed that weight loss significantly reduced, carbon yield increased after adding a certain amount of DOP. It showed that, on the one hand, the DOP played a stabilizing role, on the other hand promoted polymerization among coal tar pitch molecule. Through the analysis of polarized light microscopy and scanning electron microscopy, it showed that the structure of semi-coke obtained from co-carbonization became more order, and its compactness increased. X-ray diffraction analysis showed that the distance between the crystals surface decreased, the degree of order aromatic ring intergranular distance increased. The electrochemical results showed that co-carbonization both of CTP and DOP could improve the activity of surface electrons, thereby enhancing the ability of electron transport of carbon materials.The effect of electric field on the carbonization was studied. The structure of semi-coke was analyzed using polarized light microscopy, it showed that the electric field was propitious to form order structure of semi-coke. Further more, along with the electric field strength increasing, the structure of semi-coke became more order in a certain range. X-ray diffraction analysis showed that the distance between the crystals surface decreased, the degree of order aromatic ring intergranular distance increased. Therefore applying an electric field during the co-carbonization process also help to promote the formation of ordered structures of semi-coke. |
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