Study on Solvent Extraction of Fast Pyrolysis Bio-oil

The bio-oil, pyrolyzed in a vacuum fast pyrolysis reactor from larch sawdust, has high percentage of water (45%), low viscosity(9.80 mPa.s) and pH(2.75). The bio-oil sample was analyzed by GC/MS after filtered under vacuum conditions, which contains aldehydes(25.17%), ketons (5.56%), alcohols(1 1.35%), esters(4.46%), acids(6.54%) and phenols(20.99%). Two schemes, single stage extraction and multistage reflux extraction, were attempted to study the extraction efficiency of solvents, using cyclohexane, dichloromethane, ethyl acetate and butyl acetate. All the fractions were analyzed by GC. Of the four solvents, the efficiency of dichloromethane is highest, while cyclohexane basically has no use. Comparing with single stage extraction, the efficiency of multistage reflux extraction is as high as 1.5 to 3 times. Especially, yields of alcohols and acids, using dichloromethane, are respective 72.39% and 52.27%. However, there is a decline in the extraction for ketons and aldehydes, respectively using dichloromethane and ethyl acetate.