Catalytic hydrotreatment upgrading of biocrude oil derived from hydrothermal liquefaction of animal carcass

Abstract

Hydrothermal liquefaction (HTL) is a promising approach converting wet biomass into biocrude oil. However, the high nitrogen and oxygen content in the biocrude oil inhibit its application as a transportation fuel. In this study, HTL of the animal carcass was carried out at 320 °C for 60 min. An average biocrude oil yield of 55.6 wt% was obtained. The biocrude oil was then hydrotreated with commercial catalysts (NiMo/Al2O3 and CoMo/Al2O3), noble metal catalysts (Pt/Al2O3 and Pd/Al2O3), Mo2C, and Mo2S at 400 °C with a catalyst loading of 20 wt% for 4 h in the presence of hydrogen. CoMo/Al2O3 showed better catalytic performance regarding the nitrogen, oxygen removal, and energy recovery. Subsequently, the effect of operating temperature, catalyst loading, and residence time was investigated with CoMo/Al2O3. A maximum degree of deoxygenation and denitrogenation of 86.2% and 64.4% were achieved at 400 °C with a catalyst loading of 20 wt% for 4 h. The higher heating value of the biocrude oil was improved to 46.7 MJ·kg−1. Oil characterization results showed that upgraded biocrude oil was mainly composed of alkanes, with a small number of nitriles. The Sankey diagram shows that 37.8% of the mass, 52.7% of the energy, and 49% of the carbon were incorporated in the upgraded biocrude oil based on the animal carcass feedstock.