Investigation of controlled autoxidation of HVGO to produce carbon fibres precursors: Role of oxygen availability and mixing

Abstract

Carbon fibre is an ultra-light, strong, and durable material that has growing demand in different industries. About 95 % of currently produced carbon fibre is PAN-based which is expensive. Considering the expense and accessibility, heavy vacuum gas oil (HVGO) shows significant promise. However, it necessitates appropriate pre-treatment to generate carbon fibre precursors. The present study examined the influence of oxygen availability and mixing on controlled autoxidation (oxidation with air) in order to establish a cost-effective and efficient pre-treatment technique for assessing the feasibility of generating carbon fibre precursors from the low-value heavy petroleum fraction HVGO. Experiments were performed while maintaining temperature (130–260 ℃), time (4–24 hours), and oxygen partial pressure (N2/air) maintaining bubbling with mixing, and also blowing without mixing. Blowing without mixing at 200 ℃ for 24 h showed the highest viscosity of 7959 cP (measured at 25 ℃), and HVGO heated at 240 ℃ in 8 h in the presence N2 resulted in a maximum 26 % increase in aromaticity. It was also noticed that there was an improvement in softening point (maximum 5.4 times), volatility, and heavy products, which are crucial properties of a carbon fibre precursor. Understanding from the current research can also be applied in the area of asphalt hardening, weathering, fouling, fuel transportation and storage stability, and sludge formation.