Comparative studies on liquefaction of low-lipid microalgae into bio-crude oil using varying reaction media

Abstract

This study aimed to determine the most effective reaction medium for producing bio-crude oil from low-lipid microalgae via liquefaction treatment. To this end, the screening tests were carried out at 275 °C for 60 min by employing varying reaction media including water, water with four acid catalysts (formic acid, acetic acid, sulfuric acid, and hydrochloride acid), and four different organic solvents (methanol, ethanol, ethyl acetate, and acetone) without acid catalyst. In view of the bio-crude oil yield, methanol as the most effective reaction medium was choses for the further investigation on the effects of residence time, biomass/solvent mass ratio, and reaction temperature on the products distribution. The results showed that liquefaction at 225 °C for 60 min with a 1:5 biomass/solvent mass ratio led to the highest bio-crude oil yield of 85.5 wt% and a higher heating value (HHV) of 30.6 MJ/kg. Finally, a series of analytical approaches (elemental, GPC, TGA, GC–MS, and FT-IR analysis) were conducted for characterizing bio-crude oil.