Stabilized Pyrolytic Lignin-in-Vacuum gas oil emulsions for enhanced cracking Co-Processing Performance: Emulsification Strategies and product yield characterization

• A novel strategy for stabilizing PL-in-VGO emulsions by optimizing co-solvent and surfactant selection. • The emulsion maintained stability for 150 min at 50 °C. • Emulsification suppressed phase separation, preserving liquid product stability for over five months. • Catalytic cracking of the emulsion yielded higher-quality fuel than thermal cracking. • PL-in-VGO emulsions enhance biocrude upgrading efficiency and offer a scalable route to conventional FPO co-processing. Co-processing fast pyrolysis oil (FPO) with petroleum fuels faces challenges due to its high acidity, high oxygen content, poor miscibility, and corrosion risks. Pyrolytic lignin (PL), a key FPO fraction, offers lower oxygen content, reduced acidity, and higher heating value, making it a promising alternative for co-processing. This study introduces a novel strategy for stabilizing PL-in-vacuum gas oil (VGO) emulsions and evaluates their co-processing feasibility via thermal and zeolite-catalyzed cracking. The solubility parameter was employed as a guiding criterion for selecting an optimal co-solvent system. A mixed co-solvent of 10 wt% acetone and 90 wt% hexanol demonstrated superior emulsification performance, while sodium dodecylbenzene sulfonate (SDBS) emerged as the most effective surfactant, achieving a stable emulsion for 150 min at 50 °C at PL:VGO:co-solvent:SDBS ratio of 1:4:1:1 (w/w). Emulsified feeds enhanced upgrading performance, lowering coke (6.6 wt% vs 19.0 wt%) and gas yield (24.0 wt% vs 29.0 wt%), and increasing liquid yield (69.4 wt% vs 52.0 wt%) compared to PL alone. Compared to physical blends, emulsions also reduced coke (6.6 wt% vs. 7.6 wt%) and prevented phase separation in liquid products. Thermal cracking of the emulsions reduced coke formation and increased liquid yield, while catalytic cracking produced higher-quality liquid product. Higher catalytic cracking temperatures (530 °C vs 400 °C) favored gas over liquid yields. The results demonstrate, for the first time, that PL/VGO emulsions improve biocrude upgrading efficiency and offer a scalable alternative to conventional FPO co-processing, providing a viable pathway for integrating biomass-derived feedstocks into existing refinery infrastructures.