Asphaltene thermal treatment and optimization of oxidation conditions of low-cost asphaltene-derived carbon fibers

Abstract

This investigation is aimed at determining the conditions for the oxidation/stabilization of asphaltene fibers through extensive physicochemical characterization and evaluation of mechanical properties of the resulting carbon fibers. Melt spinning was used to fabricate green fibers using asphaltenes, from both straight solvent-de-asphalting (SDA) processing and subsequent thermal treatment. Thermal pretreatment of SDA asphaltenes was found to yield much improved carbon fiber properties. An oxidation treatment of HT300-derived (thermal pretreatment at 300 °C) carbon fibers provided the best mechanical properties with an average tensile strength of ∼1130 MPa and an average Young’s modulus of 71 GPa. Thermal treatment of SDA asphaltenes led to much lower sulfur content in both oxidized and carbonized fibers when oxidation was performed at ∼300 °C. BET, XPS, and XRD analyses showed that carbon fibers fabricated from treated asphaltenes with improved mechanical properties had a lower surface area, lower pore volume, higher amount of stable functional groups than SDA asphaltene-derived carbon fibers.