Isolation of levoglucosan from pyrolysis oil derived from cellulose

A method for preparing high purity levoglucosan from a pyrolysis oil derived from pyolysis of cellulose, comprising:

• a) mixing undiluted pyrolysis oil derived from cellulose with water and a basic metal hydroxide, oxide, or salt in an amount sufficient to elevate pH values to a range of from about 12 to about 12.5, and adding an amount of said salt in excess of said amount needed to obtain said pH range to remove colored materials of impurities from said oil and form a slurry, said amount of excess metal hydroxide, oxide or salt being about 1.5 to about 2.5 times the weight of said undiluted pyrolysis oil;
• b) drying said slurry azeotropically with methyl isobutyl ketone solvent to form a residue, and further drying said residue by evaporation;
• c) reducing said residue into a powder;
• d) continuously extracting said powder with ethyl acetate to provide a levoglucosan-rich extract;
• and
• e) concentrating said levoglucosan-rich extract by removing said ethyl acetate to provide crystalline levoglucosan.