Hydrotreating the distillate fraction of algal biocrude with used engine oil over Pt/C for production of liquid fuel

Hydrothermal liquefaction of Auxenochlorella pyrenoidosa (AuP) and Arthrospira platensis (ArP) at 350 °C for 1 h produced algal biocrudes (BCs), BC(AuP) and BC(ArP), with yields of 41.82 and 36.60 wt.%, respectively. These two algal BCs were cut into five distillate fractions (DFs) of 25–100 °C (DF0), 101–200 °C (DF1), 201–300 °C (DF2), 301–400 °C (DF3), and ≥401 °C (DR) using atmospheric distillation under N2 atmosphere. The total yields of DF1, DF2, and DF3 from either BC(AuP) or BC(ArP) are at least 60 wt.%. All the DFs, from either AuP or ArP, showed different yields and elemental and molecular compositions. Next, the DF1, DF2, and DF3 DFs were each blended with used engine oil (UEO) at a mass ratio of 1:1 and treated at 400 °C for 4 h with an additional 0.1 kgPt/C/kgfeed under 6 MPa H2. The presence of UEO could dilute the DF, avoid solvent extraction of the product oil, favor desulfurization of the upgraded oil, and be directly recovered as a major part of the product oil. Catalytic hydrotreatment of the DF and UEO blends led to a higher upgraded oil yield (>79 wt.%) and lower coke (