Production of Carbon Fiber from the Low-Molecular-Weight Compounds Prepared from Low Rank Coal and Biomass by the Degradative Solvent Extraction

摘要

The authors have recently proposed a novel degradative solvent extraction method thatrndewaters and upgrades low grade carbonaceous resources such as low rank coals and biomassrnwastes into clean products at around 350 ℃ in a nonpolar solvent. The raw materials arerndecomposed to be deoxygenated and extracted by the solvent to be separated into upgradedrncoal (UC), high molecular weight extract (Deposit), and low molecular weight extract (Soluble).rnThe properties of Solubles produced from various raw materials are almost independent of rawrnmaterials: the average molecular weights are 350 to 370, the average contents of carbon ,rnhydrogen, and oxygen are C = 80 to 83 %, H = 6.5 to 7.5 %, and O = 8 to 11 %, the ash contentsrnare less than 1.1 %. In addition Solubles completely melted below 100 ℃.rnCarbon fiber was intended to be prepared by utilizing the unique properties of Soluble.rnSoluble obtained from a rice straw in the yield of 56 % on carbon basis was used as the rawrnmaterial. First, the Soluble was film distilled at 180 to 220 ℃ to remove 10 to 15 % of smallrnmolecular weight compounds, which increased the softening temperature of the Soluble up torn250 ℃. The treated Soluble was spun by a mono-hole continuous spinner. The spun fiberrnwas stabilized in an air stream by heating it up to 300 ℃ at the heating rate of 1 ℃/min, thenrnthe stabilized fiber was carbonized in a nitrogen stream at 800 ℃ to form carbon fiber. Therncarbon fibers produced were 9 to 13 m in diameter and had tensile strength over 800 MPa.rnThese preliminary examinations showed the possibility of utilizing Solubles as raw materialsrnof carbon fiber for general purpose.