The Carbonization Of FCC Slurry By Solvent-Assisted Pretreatment

The catalytic cracking(FCC)slurry is rich in short-chain aromatics,and the refined slurry after de-solidification and deasphalting is a potential high-quality raw material for the production of needle coke.Further pretreatment of refined oil slurry is an important prerequisite for its high value utilization.Solvent-assisted carbonization pretreatment can change the association state of molecular clusters in the slurry system under certain conditions,and then affect the carbonization results in thermal conversion experiments.This paper focuses on the role of solvent in the carbonization process of FCC slurry,which has important practical significance for guiding the use of FCC slurry to prepare needle coke.In this paper,Liaohe catalytic cracking slurry was selected as the sample,the solid content was removed by distillation.The slurry was cut into different fractions,and these fractions were subjected to a carbonization test.According to the characteristics of the needle coke produced by the carbonization,the best fraction was selected as the experimental raw material for further research in the next step.Auxiliary carbonization pretreatment was carried out on the preferred fractions using solvent to investigate the effect of the pretreatment stage on the overall carbonization progress.Firstly,the basic properties of material oils were analyzed.Besides,in order to judge the stabilities of the samples after pretreatment,sedimentation point,asphaltene content and cooking time were measured.Finally,X-ray diffractometer and Microscope were used to determine the crystal lattice parameters and optical texture of the coke.Thus,the effect of solvent types,addition amount,residence time at final pretreatment temperature and heating rate on the pretreated carbonization progress were investigate.Studies have shown that the addition of different solvents during the pretreatment process had different effects.Compared with direct carbonization,the carbonization pretreated by p-xylene and p-dichlorobenzene could significantly improve the texture of coke obtained from carbonization process.Meanwhile,the anisotropic structure of the obtained cokes were increased.Between them,p-dichlorobenzene which has bigger solubility parameter had the best auxiliary function,while nitrobenzene plays a negative role in the whole process.The amount of solvent used in the auxiliary carbonization process also significantly affected the carbonization process,and the results showed that the optimum amount of p-dichlorobenzene was 10%.In the solvent-assisted carbonization process,the final temperature residence time and heating rate of different auxiliary carbonizations will also affect the character of the cokes.Under the experimental conditions,the optimum final temperature residence time was 8 hours,and the optimum heating rate was 10℃/min.