Upgrading Algae Biocrude for a Low-Nitrogen-Containing Biofuel: Compositions, Intermediates, and Reaction Routes

The upgrading of algae biocrude (obtained by hydrothermal liquefaction) was studied under mild conditions. Here we adopted a guard catalyst to protect the core catalyst and obtained algae biofuel with low heteroatom content at 350 degrees C. The nitrogen content of biofuel is 0.016 wt %, and the calculated oxygen content is less than 0.51 wt %. Furthermore, the effective yield from biocrude to a low-heteroatom-containing biofuel was close to the theoretical yield. Through a detailed study of the upgrading process, the content variation trend of biocrude and biofuel compositions and their potential reaction pathways were revealed. The results indicated that hydrogenation reactions almost finished after upgrading at 350 degrees C for 15-30 min.