Ternary Phase Diagram Of Water/Bio-Oil/Organic Solvent For Bio-Oil Fractionation

Separating bio-oil by fractionation with different chemical compositions is a critical step to refine these oils and obtain high-value products. Cold water precipitation of pyrolytic lignin from bio-oil is the most common approach used. However, the obtained aqueous phase from this method still contains phenols and is diluted and difficult to use. In this study, the use of liquid- liquid extraction with different solvents (1-butanol, ethyl acetate, 1-octanol, dichloromethane, toluene, and hexane) for the separation of targeted molecules (lignin oligomers, sugars, acetic acid) is explored. Ternary phase diagrams for the organic solvent/ water/bio-oil are reported. The partition coefficient of compounds of interest (both light and heavy fractions) is reported for the liquid-liquid equilibrium zone. When using butanol as the solvent, the highest separation factor of total phenols over total sugars was observed. Our results provide information to design L-L separation units with the capacity to selectively recover targeted molecules from pyrolysis oils.