Production of biocrude from organic waste: Influence of feedstock composition on hydrodenitrogenation reactivity in biocrude upgrading

Hydrothermal liquefaction (HTL) process of protein-rich biomass produces biocrude with a high nitrogen content that hinders its use as a biofuel intermediate. Nitrogen compounds in the biocrudes are mainly present as fatty acid amides (FAAs) and nitrogen-containing polycyclic aromatic compounds (NAs), having different hydrodenitrogenation reactivity during the biocrude upgrading process. Therefore, it is crucial to shift reaction pathways towards the formation of less recalcitrant compounds and reduce the nitrogen content of the biocrudes. Herein, the impact of the chemical composition, in particular a lipid content, on the biocrude yield, nitrogen content and types of nitrogen species has been studied using macromolecular model compounds. By comparing the hydrodenitrogenation (HDN) reactivity of FAAs and NAs, it was found that the latter are more recalcitrant compounds compared to the FAAs and that the higher lipid content inhibits the generation of NAs. These results suggest that lipids-rich waste can be supplemented with food waste to produce the biocrudes highly suitable for conventional hydrotreatment processes.