Optimization of a Mixed Additive and its Effect on Physicochemical Properties of Bio-Oil

A final optimal mixed additive consisting of methanol, acetone, and ethyl acetate in specific proportions was obtained by one-factor multi-objective optimization of the Design-Expert software and performed well in a verification experiment. The mixed additive of methanol and ethyl acetate was first prepared separately and then added to bio-oil, followed by acetone. The viscosity of the additive/bio-oil mixture was significantly lower than of the crude bio-oil. Among all chemical compound groups in the bio-oil, the content of phenols was the highest one. Chemical compounds in bio-oil after aging had higher molecular mass weights than before. The addition of the final optimal mixed additive and the accelerated aging process could slightly change the intensity and positions of some absorption peaks.