Evaluation of the coprocessing feasibility of bio-oil extraction fractions with waste cooking oil for 100 % bio-based fuel production in a pilot-scale riser

Fast pyrolysis oil (FPO) has a high oxygen content, which usually requires hydrogenation pretreatment before coprocessing to produce biofuels. In this study, a simple stepwise solvent extraction was applied instead of hydrogenation. The n-hexane-insoluble fraction (which performs poorly) was removed. The remaining fractions were then coprocessed with either vacuum gas oil (VGO) or waste cooking oil (WCO), and no major changes were observed in product distribution or quality. These results indicate that even low-grade FPO can still undergo effective cracking. Experimental findings also show that adding the aqueous phase of FPO increases LPG production, while adding the water-insoluble/n-hexane-soluble fraction (WIS-HS) enhances gasoline yield. However, mixing the water-insoluble/n-hexane-insoluble fractions (WIS-HIS) at 5 wt % leads to operational instability, reduced conversion, and heavier coke formation. This suggests that the highly polymerized pyrolytic lignin in WIS-HIS is mainly responsible for poor FPO cracking. It was further demonstrated that coprocessing pure WCO with WS (10 wt %) or WIS-HS (5 wt %) is feasible without adversely affecting product distribution or quality. Overall, these findings open new possibilities for utilizing low-quality biomass resources FPO and WCO in biofuel production.