Isolation of Levoglucosan from Lignocellulosic Pyrolysis Oil Derived from Wood or Waste Newsprint
U.S. Patent 5,432,276
Technology Description A method is provided for preparing high purity levoglucosan from lignocellulosic pyrolysis oils derived from wood or waste newsprint. The method includes reducing wood or newsprint to fine particle sizes, treating the particles with a hot mineral acid for a predetermined period of time, and filtering off and drying resulting solid wood or newsprint material; pyrolyzing the dried solid wood or newsprint material at temperatures between about 350.degree. and 375.degree. C. to produce pyrolysis oils; treating the oils to liquid-liquid extraction with methyl isobutyl ketone to remove heavy tar materials from the oils, and to provide an aqueous fraction mixture of the oils containing primarily levoglucosan; treating the aqueous fraction mixtures with a basic metal salt in an amount sufficient to elevate pH values to a range of about 12 to about 12.5 and adding an amount of the salt in excess of the amount needed to obtain the pH range to remove colored materials of impurities from the oil and form a slurry, and freeze-drying the resulting slurry to produce a dry solid residue; and extracting the levoglucosan from the residue using ethyl acetate solvent to produce a purified crystalline levoglucosan.
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