Extraction of Lipids from Chlorella Alga by Supercritical Hexane and Demonstration of Their Subsequent Catalytic Hydrodeoxygenation

Abstract

Extraction of lipids from Chlorella algae with supercritical hexane resulted in the high lipids yield of approximately 10% obtained at optimum conditions in terms of extraction time and agitation compared to the total content of lipids being 12%. Furthermore, an easiness of hexane recovery may be considered as economically and ecologically attractive. For the first time, in the current work catalytic hydrodeoxygenation (HDO) of Chlorella algal lipids was studied over 5 wt % Ni/SiO2 at 300 °C and under 30 bar total pressure in H2. The conversion of lipids was about 15% as the catalyst was totally deactivated after 60 min. The transformation of lipids proceeded mostly via hydrogenation and hydrogenolysis with formation of free fatty acid (FFA). Lower activity might be attributed to deactivation of catalysts caused by chlorophylls and carotenoids. Even though the conversion is low, future studies in HDO of lipids extracted from other algae species having higher lipid content could be proposed. A coke resistant catalyst might be considered to improve catalytic activity.

Direct hydrodeoxygenation of algal lipids extracted from Chlorella alga

“…Algal lipids were extracted from Chlorella alga by supercritical hexane. 16 The fatty acids content in the algal lipid was 53.59 ± 0.17 wt%. In addition, the feedstock contained also 0.25 wt% sulfur and 4.01 wt% nitrogen, based on organic elemental analysis.…”

“…Algal lipids were extracted from Chlorella alga by supercritical hexane . The fatty acids content in the algal lipid was 53.59 ± 0.17 wt%.…”

“…The fatty acids content in the algal lipid was 53.59 ± 0.17 wt%. In addition, the feedstock contained also 0.25 wt% sulfur and 4.01 wt% nitrogen, based on organic elemental analysis . Other chemicals used were of analytical grade.…”

“…In addition, the feedstock contained also 0.25 wt% sulfur and 4.01 wt% nitrogen, based on organic elemental analysis. 16 Other chemicals used were of analytical grade. Table 1 presents the fatty acid profile of the algal lipids after transesterification required for analysis.…”

“…While HDO of triglyceride, free fatty acids (FFA), and their derivatives has been widely studied, information on HDO of lipids extracted from alga is rather limited. The aim of this work was to demonstrate for the first time hydrodeoxygenation of crude Chlorella algal oil extracted with supercritical hexane as solvent with nickel and molybdenum‐based catalysts. For comparison purposes, HDO of stearic acid was also studied with the same catalysts.…”