From Coal-Heavy Oil Co-refining Residue to Asphaltene-Based Functional Carbon Materials

Asphaltene-based carbon fiber, needle coke, and porous carbon nanosheets were synthesized using the extracted asphaltene from coal-heavy oil co-refining residue. Asphaltene with high average molecular weight and aromaticity is considered proper to be polymerized or cross linked, and is a high-performing precursor to synthesize carbon materials. It can be transferred into pitch after pyrocondensation polymerization; the resultant asphaltenebased carbon fiber with a tensile strength of 0.92 GPa was obtained via spinning, preoxidization, and carbonization. While high graphitized needle coke was formed when asphaltene underwent thermal polycondensation, delayed coking, and carbonization, it provided a facile route to produce needle coke from asphaltene. A porous carbon nanosheet with a high surface area of 1717 m2/g and pore volume of 0.94 cm(3)/g was synthesized using asphaltene as carbon precursor, melamine as nitrogen resource, and molten salt as template; the porous carbon nanosheet showed high CO2 adsorption amount and outstanding adsorption selectivity for CO2-N2 and CO2-CH4. It indicated that asphaltene was an excellent precursor to prepare functional carbon materials for its adjustable molecular weight distribution, high aromaticity, controllable thermal condensation, and easy graphitization. It provided an effective strategy to tailor solid residue from coal and heavy oil co-refining and developed directional conversion or utilization of asphaltene.