Study On The Mesophase In The Process Of Needle Coke Preparation From FCC Slurry

Accelerating the development of high-quality needle coke production technology, and achieving high-quality needle coke localization are important issues which should be solved immediately. During the process of preparing needle coke, the structure and morphology of carbonaceous mesophase directly determines the various properties of needle coke. Therefore, improving the carbonaceous mesophase structure is an effective way to improve the quality of needle coke. This paper investigated the format process of carbonaceous mesophase which used the FCC slurry as raw materials, and also studied the impact of process conditions and feedstock compositions on the structure of the mesophase, and finally proves the relationship between the raw materials and mesophase structure during the preparation of mesophase by the model compounds.In order to investigate the impact of carbonization conditions on the mesophase formation process, three kinds of catalytic cracking slurry from Zhenhai Refinery was treated under different conditions after vacuum distillation and hydrotreating, then the mesophase were analysed under the Polarizing Microscope. It was found that the mesophase formation process included the generation of nuclei, growth and coalescence of the anisotropic spheres, and the formation of the flow domain. For preparing flow domain, Zhenhai FCC slurry without pretreatment was needed to be treated under450℃for12hours, while the slurry after vacuum distillation was needed to be treated under460℃for12hours and the slurry after vacuum distillation and hydrotreating was needed to be treated under460℃for15hours. The laws of carbonization conditions on the mesophase, can guide the choice and optimization of operation conditions in industrial production.Three group distillates were carbonized in pyrex tube to prepare the mesophase. It showed that the structure of mesophase was decreased with the increase of boiling point and relative molecular weight of raw materials as well as the carbon residue and resin content. Taking distillated of Zhenhai FCC slurry as raw materials, we studied the impact of composition of feedstock on the mesophase structure. The results showed that the mesophase structure was increased with the increasing of the contents of monocyclic, bicyclic, tricyclic aromatic hydrocarbons, while as the contents of five plus rings aromatic hydrocarbons and alkanes increasing, the optical structure of mesophase was decreased. Three kinds of model compounds were used to prepare the mesophase. Results indicated that the1-methylnaphthalene could transfer to flow domain, while the pyene just formed the mosaic structure under the same treatment conditions, and the pure phenanthrene could formed the domain structure.