Study Of The Aromatic Structure Of FCC Slurry And Preparation Of Needle Coke

Fluid catalytic cracking(FCC)slurry,which is dense,viscous and contains a lot of catalyst dust,is used by most refiners as low value added fuel oil.It is not only economically inefficient,but also causes a great waste of resources.FCC slurry contains a large amount of polycyclic aromatic hydrocarbons,and it can be used as high value-added products of raw materials after processing.To study the structure and composition of aromatics in different narrow fractions of oil slurry,the extracted oil of intermediate base and paraffinic base FCC slurry were divided into eight narrow fractions by vacuum distillation.The improved B-L method and Comprehensive Two-dimensional Gas Chromatography/Time of Flight Mass Spectrometry(GC×GC-TOF MS)used to investigate the changes of aromatics composition and structure in each narrow fraction of two kinds of slurry.The feasibility of preparing needle coke was studied by selecting some distillate as raw material.The results showed that the QD-FCC slurry of intermediate base was mainly composed of3～5 ring aromatics.The LZ-FCC slurry of paraffinic base was mainly composed of 2～4 ring aromatics.The total saturated-carbon ratio and naphthenic-carbon ratio of LZ-FCC slurry were more than its of QD-FCC slurry.The tricyclic aromatic hydrocarbons was mainly included phenanthrene and dihydrobenzanthracene compounds for both FCC slurry;the tetracyclic aromatic hydrocarbons was mainly included benzanthracene compounds and few of pyrene compounds;the pentacyclic aromatics was mainly benzopyrene compounds.The pentacyclic aromatics of LZ-FCC slurry was far less than that of QD-FCC slurry.Some specific narrow fractions were selected for the experiment to explore the feasibility of preparing needle coke.The optimum conditions for preparing semi-coke are 480℃,2 MPa,10℃/min(rapid heating)from room temperature to 320℃,and 2～3℃/min from 320℃ to480℃.Under these conditions,the yield of semi-coke is about 70%,and its structure is arranged evenly and orderly,and the area of wide-area and streamline structure is very large.The elemental composition as well as microstructure of semi-coke are greatly improved,and the graphitization degree is further strengthened by high temperature calcination at 1400℃.