Bio crude oil production using catalytic hydrothermal liquefaction (HTL) from native microalgae harvested by ozone flotation
Abstract This work explored bio crude oil production and the hydrocarbon distribution resulting from a catalytic HTL process with a feedstock composed by native consortium of microalgae (mostly cyanobacteria) with low lipid and high protein content. Two harvesting methods ozone flotation and centrifugation were compared. Also, the effect of the catalysts, HZSM 5 zeolite, content (0, 5 and 7 wt% loading with respect to dry biomass) were studied. The dry biomass was liquefied in water (slurry at 4 wt% at 350 degC for 120 min. Results showed that the bio crude contained aliphatic, aromatic, cyclic, oxygenated cyclic and aliphatic compounds containing N and O, with a bio crude yield of between 10 and 16% The best quality of bio crude oil was produced from microalgae harvested and pretreated by ozone flotation at 7 wt% HZSM 5. The increase in the bio crude quality was a result of a lower nitrogen (3.2% oxygen (4.8% and sulfur (0.7% content versus centrifuged (no catalyst) microalgae 4.6% 7.9% and 1.6% respectively.
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