Structural evolution of coal liquefaction residue and preparation characterization of coated pitch with high softening point
The low ash coal liquefaction refined pitch was obtained by deashing and desolidifying through the 350,000 t oil residue ex-traction device of coal-to-oil Company,and was separated by different solvents to get heavy oil,asphaltene and pre-asphaltene.An av-erage molecular structure model was initially constructed,And the results show that the basic structures of the three components are cy-cloalkanes,polycyclic aromatic hydrocarbon linked alkyl side chains and units containing heteroatoms.And the structural units form a complex between them.The active centers of each molecule are mainly distributed in the double bonds of the benzene ring and the O re-gion of the active atom,and asphaltene and pre-asphaltene have high activity.In order to fully utilize coal liquefaction refined pitch,a high softening point coated pitch was prepared by air oxidation method.The effects of air flow rate,oxidation temperature and time on the softening point and coking value of the prepared coated pitch were explored.The oxidation condensation process was analyzed and summarized using ATR Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy,and NMR nuclear magnetic reso-nance spectroscopy.The results show that when the stirring speed is 360 r/min,the reaction time is 2～3 h,the reaction temperature is 310～320℃,and the air flow rate is 1.5～2 L/min,high-quality coated pitch with a softening point of 205℃and 245℃can be pro-duced,respectively.Subsequently,the parallel comparative tests for the electrochemical properties were conducted on the original graph-ite,petroleum based coated pitch,and the two batches of coal liquefaction coated pitch mentioned above.The results show that coal liq-uefaction coated pitch with a softening point of 245℃has significant performance advantages in terms of rate and long cycle perform-ance compared to oil based coated pitch with a softening point of 280℃,which can effectively improve the electrochemical performance of raw graphite,broaden the application field of coal liquefied pitch,and provide a new approach to prepare coated pitch.
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