Influencing factors of coal liquefaction residue induced polycondensation to prepare metallurgical coke
The asphaltene and heavy oil contained in coal liquefaction residue can generate a large number of free radicals during pyrolysis.If they cannot be stabilized and polycondensation in time,they will be transformed into a large number of tar and gas,forming pore struc-ture,affecting the density of metallurgical coke.Therefore,a certain amount of additives to induce high efficiency polycondensation was introduced,polymer density was improved,high-quality metallurgical coke was prepared after carbonization.The effects of different addi-tives(furfural,methanol,furan and hydroxyacetone),temperature(350,400,450,500 and 550℃),residence time(0,30,60 and 120 min)and addition amount(0,4,8 and 16 g)on the polycondensation rate,structural properties,density and thermal stability of the prepared polymer were systematically studied.The optimum experimental conditions for induced polycondensation of coal liquefaction resi-due were obtained.Under the optimal conditions,the surface morphology,microcrystal structure and element changes of the prepared pol-ymer and carbonization were investigated respectively,and the induced polycondensation mechanism of coal liquefaction residue was ob-tained.The results show that the additive(furfural)have the best effect on inducing polycondensation,followed by hydroxyl acetone.Therefore,the superior additive should contain at least one aldehyde or ketone group.The different additives can promote the polyconden-sation of coal liquefaction residue and increase the specific surface area,pore volume,average pore size and true density of the polymer.The temperature and residence time have great influence on the thermal stability and surface properties of coal liquefaction residue/furfural polymer.The increasing temperature and residence time can promote the phenolic groups and H of aromatic compounds in the coal lique-faction residue to participate in the polycondensation reaction and improve the polycondensation'degree of polymer.The coal liquefaction residue/furfural(coke)is lamellar dense and contains more amorphous carbon.
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