Preparation Of Mcmbs From Supercritical Fluid Fractions Of DQ FCC Slurry Oil

Large quantities of fluid catalytic cracking(FCC)slurry oil(SLO)are produced each year in China,but the utilization efficiency and economic benefit of the slurry are poor.FCC SLO mainly constitutes of polynuclear aromatic hydrocarbons(PAHs),which are favorable feedstocks for high value-added carbon materials.Mesocarbon microbeads(MCMBs)have been widely used in many fields for excellent chemical stability and electrical conductivity.However,due to the catalyst particles and metals in slurry oil,it is difficult to obtain ideal MCMBs through general carbonization method.DQ FCC slurry oil(DQ SLO)were separated into a set of fractions by Supercritical Fluid Extraction and Fractionation(SFEF)with iso-butane and n-pentane as solvent.The properties,compositions and structures of FCC slurry oil and its SFEF fractions were studied.It was found that properties of sub-fractions were enhanced and most heavy components were enriched into the end-cut.DQ SLO was used as feedstock for carbonization process to get a deeper insight into the effect of temperature and reaction time on MCMBs preparation.Polarized microscopy,SEM,XRD and Raman spectrum were applied to compare the morphology and quality of the carbonization products.The results showed that high temperature and long reaction time could accelerate the formation and development of the mesophase.420 °C/3 h was chosen as the optimum reaction condition for the preparation of MCMBs with DQ SLO as feedstock.SFEF fractions separated by supercritical extraction of two different solvents were used as feedstock,the effect of pressure on the properties of mesophase products was investigated at 420 °C/3 h.It was found that products qualities could be optimized by controlling reaction pressure but it did not play a decisive role.The optimum reaction pressure gradually decreased as the extracted fraction became heavier.Both alkyl carbon and aromatic carbon content were key factors influencing the development of carbonaceous mesophase.Based on MCMBs preparation performance of light and heavy fractions separated by two solvents,iso-butane was selected as the optimized SFEF solvent.MCMBs of higher qualities were produced from SFEF fractions.The results indicated that supercritical fluid extraction can be used to improve the quality of produced MCMBs by removing undesirable components.The molecular transition law of reaction matrix under different conditions was investigated.It was found that as the progress of the reaction deepened,the condensation of matrix increased.There was no change in the types of heteroatom compounds before and after carbonization.Moreover,during the progress of the reaction,compounds of low condensation reacted preferentially.