Role of oxidative pretreatment on asphaltenes enhancement for carbon fiber precursor production from vacuum residue (VR)

There is growing interest in utilizing petroleum residue to useful carbon materials for economic diversification of low-value petroleum byproducts. Due to chemical complexity and the presence of impurities, it requires pretreatment which traditionally involves two steps: autoxidation to increase asphaltenes content and solvent deasphalting to remove lighter compounds, leaving purified asphaltenes. However, in this study, these two steps were combined into a single autoxidation process investigating the effects of temperature, time, and tetralin addition. Remarkably, the samples obtained after autoxidation were successfully processed through the melt-spinning machine without requiring the solvent deasphalting step. The highest asphaltenes yield of ∼77 wt% was achieved at 280°C for 10 days, with a softening point of 191°C, while adding 4 % tetralin at 190°C produced 73.2 wt% asphaltenes with a softening point of 169°C, demonstrating enhanced reactivity under milder conditions. Vacuum residue-derived asphaltenes exhibited high thermal stability, retaining 35 % of their weight at 800°C, and produced carbon fibers with diameters of 40–50 µm and a carbon content of 92.6 wt% after carbonization at 900°C. This approach offers a cost-effective pathway to convert low-value petroleum fractions into high-value materials while addressing production challenges. • The study investigates carbon fiber precursor production from vacuum residue (VR). • Oxygen availability, mixing, and naphthenic-aromatic hydrocarbon greatly influenced the free radical chemistry. • Green fiber was successfully produced from autoxidized VR without requiring the solvent deasphalting step.