Carbon fibers (CFs) are valuable in applications such as aircraft, automobiles, wind turbines, and energy storage devices. However, the production cost of CFs is high due to the use of conventional precursor polyacrylonitrile, and an affordable substitute is imperative. For the first time, this work combined cheap coal and waste plastic material to fabricate CFs. Currently, conventional disposal methods for waste plastics lack sustainability and profitability. Despite its unpopularity as an energy source, coal can serve as a feedstock for chemicals and materials. High-density polyethylene (HDPE), a commonly used plastic, was hydrogenolyzed into a plastic-derived liquid (PDL). PDL served as an effective solvent during mild solvolysis liquefaction of coal, and the acquired coal–plastic liquid was modified into mesophase coal–plastic liquids (MCPLs). MCPLs were melt-spun and heat-treated into CFs through different heat treatment conditions. The diameters of the CFs were 8.2-45.8 μm, and the Young's modulus and tensile strength were 75-759 GPa and 0.54-4.03 GPa, respectively. The CFs belong to the categories of general-purpose and high-performance CFs. The high-performance CFs (diameter: 8.2 μm, Young's modulus: 759 GPa, and tensile strength: 4.03 GPa) are comparable to commercial and laboratory CFs whose precursors are coal-tar pitch featuring low coal-to-pitch yield, or coal liquefied by conventional, costly solvents. Analysis shows the PDL enhances hydrogen transfer, stabilizes radicals, and promotes mesophase development during thermal treatment. The mechanisms valorizing coal and plastics simultaneously to high-performance CFs are proposed. This work demonstrates a novel and sustainable valorization pathway for waste plastics and coals. Future work will explore industrial-scale plant design, techno-economic analysis, and life-cycle assessment to quantify the economic and environmentalimpacts.

The purpose of this study was to prepare a proof-of-concept CO₂ adsorbing material based on a new amine grafted silica aerogel microsphere (AGSAM) that could be used on both fixed and fluidized beds. A low-cost water glass and environment-friendly water were used as precursor and solvent of the silica aerogel, respectively. The silica aerogel microsphere (SAM) was prepared by dropping the siliceous solution into hot oil bath. The effect of the pH value of the siliceous solution, stirring speed and stirring paddle position on the sphericity and size of the SAM was investigated. The SAM with good sphericity was obtained when the pH value was 5.69–5.79. The mean diameter of the SAM decreased from 5 to 1 mm when the stirring speed increased from 1000 to 2000 rpm. The SAM with excellent sphericity was prepared when the paddle was placed on the top of the oil bath. When the paddle was placed at the middle and bottom of the oil bath, some liquid drops aggregated together and formed large aggregations. AGSAM was obtained by grafting the amine groups onto the framework of the silica gel microsphere. The CO₂ adsorption capacity of the AGSAM was 1.04 mmol g^-1 with 1% CO₂ at 300 mL min^-1. The AGSAM with 4, 3.2, 2 and 1 mm in diameters had the fluidizing velocities of 0.531, 0.425, 0.265 and 0.159 m s^-1, respectively. The AGSAM with different sizes met different fluidizing conditions.