Catalytic Conversion of Chlamydomonas to Hydrocarbons via the Ethanol-Assisted Liquefaction and Hydrotreating Processes

Ethanol-assisted liquefaction followed by a hydrotreating process has been applied to the microalgal biomass of Chlamydomonas. The intent of the research was to develop process technology to convert microalgae into drop-in fuels. The operation conditions of the ethanol-assisted liquefaction were optimized using the following variables: reaction temperatures (200-290 °C), ethanol concentration (10-90 vol. %), residence time (0.5-2 h), and the catalyst (SO₄^2-/ZrO₂). The application of a higher ethanol concentration and the solid acid enhanced extraction of algal lipids and transesterification. The highest liquid yield of 93.7% for catalytic liquefaction was obtained under the reaction conditions of (290 °C, 90 vol. % ethanol, and 0.5 h). Hydrotreating of the liquid products generated via liquefying microalgae was conducted over a Mo₂C/Biochar catalyst at 340 °C and 3.44 MPa hydrogen. The obtained products contained predominantly hydrocarbon molecules falling into the diesel range.