Preparation of pitch-based general purpose carbon fibers from catalytic slurry oil

• Polymerization leads to bigger QI particle size and easier removal.
• Polymerization makes more active components convert into QI preferably.
• Polymerization suppresses secondary QI during subsequent processes.
• Longer polymerization makes carbon fiber properties more uniform.
• Extraction can effectively increase softening point without generating secondary QI.

Preparation of high-value pitch-based carbon fiber from catalytic slurry oil is of great importance, but is very difficult with traditional routes. In this work, a new route studied on the development of suitable pitch precursor from catalytic slurry oil was carried out using the techniques of thermal polymerization to increase the content of heavy components, centrifugal separation to remove the quinoline insolubles (QI), solvent extraction to remove light components and vacuum distillation to remove extractant. The effects of the above treatment processes on the QI particles size distribution, thermo-gravimetry, other properties of asphalt, micro-structure of pitch fibers and mechanical properties of carbon fibers were investigated. The result showed that thermal polymerization could significantly improve the contents of heavy components, accelerate the conversion of active components (alkenes, heterocycles, etc) into QI, and greatly increase QI particles size. The process of solvent extraction could effectively remove the light components and increase the softening points of asphalt. With increasing the time of thermal polymerization, QI particles became bigger and more easily removable, the micro-structures of pitch fibers were much smoother, and the mechanical properties of carbon fibers were more uniform.