Research On Fractional Extraction Of High Temperature Coal Tar For Preparing Coal-based Jet Fuels

High temperature coal tar is rich in aromatic compounds and is an ideal material for preparing high performance coal-based jet fuel(naphthene and hydrogenated aromatics).In this paper,with n-hexane and toluene as solvent,respectively,to fractional extraction of high temperature coal tar,studied the main factors influencing the grading extraction yield,composition and distribution of fractional extraction and wash oil with high temperature coal tar distillation cut and anthracene oil fractions were compared;the preparation of coal-based jet fuel from high temperature coal tar and high temperature coal tar was carried out by hydrotreating.The catalytic mechanism of preparation of coal-based jet fuel by hydrogenation of high temperature coal tar was studied by using catalyst characterization and model compound probe reaction.Research indicates:(1)Ultrasound-assisted method is beneficial to improve the yield of coal tar fractionated extracts,especially n-hexane extracts.The extraction rate of n-hexane was increased to 39.3%by ultrasound-assisted fractional extraction,and the total extraction rate increased from 80.6%to 86.2%by mechanical agitation,but the n-hexane raffinate of both extractions Toluene ultrasonic extract yields were almost equal.Temperature is an important factor in affecting the yield of high-temperature coal tar fractionation extract.When the extraction temperature is increased from 0°C to 30°C,the extraction rate of high-temperature coal tar from hexane increases from 30.8%to 39.3%;the total extraction rate increases from 77.2%to 86.2%.(2)The composition and distribution of coal tar graded extracts are quite different.The n-hexane extract is mainly composed of 1?3 ring aromatic compounds,which is equivalent to the oil distillate cut with high temperature coal tar distillation;the N-hexane extraction tailing toluene extraction is given priority to with 4?6 ring aromatic hydrocarbons,and high temperature coal tar distillation separation compared to cutting anthracene oil fractions,4?6 ring aromatic hydrocarbons by anthracene oil content of 18.8%to 76.5%.(3)When the preparation of the coal-based jet fuel by hydrogenation of the coal tar hexane extract,the active component of the catalyst was the key factor affecting the hydrofining performance.Due to the presence of a certain amount of heteroatom compounds containing S,N and O in the n-hexane extract,the active components of Ni/?-Al₂O₃and Cu-Ni/?-Al₂O₃catalysts are easily inactivated by poisoning,while Ni Mo S/?-Al₂O₃(UDS-6)catalyst has a strong S,N,and O tolerance due to the active component Ni Mo S,the hydrofining properties of the more excellent n-hexane extract were shown,and the content of naphthene and hydrogenated aromatic hydrocarbons in hydrogenated products accounted for 67.4%of the whole product,and the coal based jet fuel was produced by subsequent separation.(4)Hydrogenation of toluene extracts of coal tar-hexane raffinate toluene extract,when preparing coal-based jet fuels,the acidity of the catalyst is a key factor affecting the performance of hydrotreating.The toluene extract of n-hexane raffinate is mainly4?6-ring aromatic compounds and requires partial ring-opening cracking to obtain jet fuel.The ring-opening cracking of aromatic rings requires the catalyst to have a certain amount of acid and protonic acid(B acid).Since the Ni Mo S/?-Al₂O₃(UDS-6)catalyst has a low acid content and is basically Lewis acid(L acid),the toluene extract of the n-hexane raffinate has almost no hydrogenation activity;in addition,The metal-Ni catalyst with multistage ZSM-5 load(Ni/ZSM-5(SA))has a certain strength and acid amount of protonic acid(B acid),and it shows a better hydrogenation performance of toluene extract from a relatively superior n-hexane extract.(5)Ultrasonic assisted preparation of coal-based jet fuel by hydrogenation of the toluene extract of the coal tar n-hexane raffinate has a significant role in promoting.It is mainly composed of 4-6 cyclic aromatic hydrocarbons,and its molecular size is large.During the hydrogenation reaction,the diffusion efficiency of the mass transfer is an important factor affecting the hydrogenation performance,combined with the difference in high-temperature coal tar distillation and cutting.Molecular size of the oil wash and olein fraction hydrogenation experimental results,found that ultrasound-assisted due to its unique"cavitation"effect,hydrogenation reaction,involving macromolecular reaction system(anthracene oil,hexane extraction tailing toluene extract)of diffusion and mass transfer have a significant role in promoting,can significantly improve the n-hexane extraction tailing toluene extraction yield of hydrogenation product.