Hydro-upgrading of algal bio-oil in tetralin for the production of high-quality liquid fuel: Process intensification

We report a new process to realize the deep removal of N, O, and S from the bio-oil when using a batch reactor to do the hydro-upgrading experiments. That is, within a fixed reaction time, hydro-upgrading of the bio-oil was carried out in several stages. After each stage reaction was finished, the reactor was cooled, and the gas in the reactor was replaced with fresh hydrogen, and then the reaction continued until the total reaction time was complete. A bio-oil produced from hydrothermal liquefaction of microalgae mixed with tetralin at a mass ratio of 1:1 was used as the feedstock. The experiments were performed at different temperatures (300-480 degrees C) and time (1-8 h) with fixed addition of 10 wt% Pt/C and 8 MPa H-2. Higher treated bio-oil yield was always achieved if the reaction was performed in several stages. The N-, O-, and S-containing compounds in the gaseous products mainly consisted of C2H4N, C3H7N, C6H7N, NH3, (SCN)(2), SO2, and H2O. The removal of these gas products avoided their secondary reactions with the bio-oil and slowed down the catalyst poisoning, and thus breaking through the equilibrium limitations of denitrogenation, desulfurization, and deoxygenation and prolonging the activity of the catalyst.

Automated summary

Performing the hydro-upgrading process in multiple stages can increase the yield of processed bio-oil and prevent the gas products from undergoing secondary reactions with the bio-oil. The removal of nitrogen, oxygen, and sulfur compounds can prolong the activity of the catalyst.