Valorization of thermochemical conversion of lipid-extracted microalgae to levulinic acid.

Scenedesmus obliquus, a green microalga of the class Chlorophyceae, has been used to produce biofuels. However, limited research has been reported on platform chemicals that use microalgae as biomass to replace fossil sources. This paper reports on the investigation of levulinic acid (LA) production from lipid-extracted S. obliquus with an acid-catalyzed thermochemical conversion using a statistical experimental approach. For the reaction factors, the highest effect on LA yield resulted from catalyst concentration. The optimized LA yield of 45.63 wt% (70.7 mol%) was achieved with 5 wt% lipid-extracted microalgae and reaction factors of 0.85 M HCl as a catalyst at 180 °C for 10 min. Also, the LA yield as a function of the combined severity factor followed a sigmoid curve. High LA yield resulted from combined severity factors greater than 3.4. These results indicate that the production of platform chemicals may be possible using microalgae feedstocks and thermochemical conversion.