Influence of two asphaltenes on the formation and development of mesophase in fluid catalytic cracking (FCC) slurry oil

Abstract

Asphaltene constitutes the heaviest component in fluid catalytic cracking (FCC) slurry oil. Mesophase pitch are prepared from FCC slurry oil by adding two asphaltenes (CL-As/JB-As) with distinct structure, and the influence of asphaltenes on the formation of mesophase is investigated. The findings suggest that an addition of CL-As within the range of 0–20 wt% is advantageous for the development and formation of mesophase. The addition of JB-As less than 1 wt% facilitates the formation and development of mesophase, while the opposite is observed with JB-As greater than 1 wt%. This is due to the light fraction of JB-As (JB-As-L), which is similar to CL-As and possesses appropriate concentrations of reactive sites that promote the formation of mesophase. However, the prevalence of alkane-branched chains is most densely concentrated in the heavy fraction of JB-As (JB-As-H), which leads to an excessive concentration of reactive sites. The predominance of JB-As-H causes an increase of the system's viscosity in the early stage so that the collision of polycyclic aromatic hydrocarbon macromolecules is reduced and the formation of the mesophase is postponed eventually. This provides a profound understanding of the preparation of high-quality mesophase pitch by regulating the properties of raw materials.