Biochemicals to enable biorefining: a case study of polyphenol extraction from bio-oil for utilization as a biodiesel antioxidant†

Although bio-oil from biomass pyrolysis can be hydrotreated or cracked into transportation fuel, economic and energy challenges remain. One strategy is the cogeneration of oxygen-containing biochemicals with high value in biorefining. Here, we developed a simple separation method a with combination of distillation and chemical extraction to produce a stream of mixed phenolic compounds, the potential of which as a sustainable biodiesel antioxidant was explored. The study revealed that higher distillation temperatures (>250 °C) contributed to the enrichment of methoxyphenols, binary phenols and ternary phenols. The presence of electron-withdrawing groups at the ortho and para positions to phenolic hydroxyl groups was found to enhance antioxidant activity. An increase in the number of phenolic hydroxyl groups also significantly improved antioxidant performance. Certain extracts with the maximum amount of pyrogallol and binary phenols exhibited comparable antioxidation performance to commercial antioxidants. Acetic acid, cyclopentanone, furfural, and benzyl ether exhibited a certain negative effect on antioxidant activity. Based on these findings, a graded utilization strategy for pyrolysis bio-oil was developed, and the economic feasibility was comprehensively evaluated. The minimum sales price of the biodiesel antioxidant was calculated to be $1072.98 per ton, which is significantly lower than the market price of commercial antioxidants, indicating the economic potential of this strategy.