Catalytic hydrotreatment of biocrude from hydrothermal liquefaction of wet-waste: Effect of parameters and catalysts on upgraded fuel properties

• HTL biocrude distillates were hydrotreated using different catalysts and parameters. • Non-noble metal catalysts were compared, with highest heteroatom removal from CoMo. • Regression showed high correlation between reaction parameters and fuel properties. • Reaction conditions could be tuned to achieve desirable properties. Hydrothermal liquefaction enables recovery of carbon and energy from wet wastes, producing a biocrude that can be upgraded into renewable transportation fuels such as diesel and sustainable aviation fuel. However, HTL biocrude is typically featured by high heteroatom content, hindering its fuel properties. While previous work has investigated the effects of hydrotreating parameters including catalysts on heteroatom removal, this study sought to develop additional insights on their effect on upgraded fuel properties. Molybdenum alloy (CoMo, NiMo, Mo 2 C) and precious metal (Pt, Pd) catalysts were compared. Hydrotreating conditions from 350–450 ○ C , 0.1–0.5 catalyst:oil weight ratio, 2–4 h, and 10–20 hydrogen:oxygen mol ratio were explored. The hydrotreated HTL biocrude demonstrated high oil, carbon, and energy yields (45–90% for all), along with up to 93 wt% total heteroatom removal (100% HDO, 89% HDS, 19% HDN). It was found that molybdenum-based catalysts had comparable performance to noble metal catalysts like platinum and palladium, achieving complete deoxygenation and producing high fractions in the gasoline, kerosene, and diesel range. Temperature, catalyst load, and retention time significantly impacted the conversion efficiency and fuel properties. Furthermore, fuel properties of the hydrotreated biocrude could be accurately predicted using a regression model with good fit (R-squared 0.85–1.00). Accordingly, hydrotreating conditions can be tuned to optimize carbon and energy recovery, target fuel ranges, and desired hydrocarbon types. This work contributes to the recovery of renewable carbon from waste biomass, enabling the advancement of circularity for transportation fuels.