Intermediates for synthetic paraffinic kerosene from microalgae

Intermediates for synthetic paraffinic kerosene with structures of fatty acid methyl ester (FAME), were synthesized from algal oil extracted from Nannochloris sp. biomass. Microalgae were grown under mixotrophic conditions to improve biomass production, using glycerin as additional source of organic carbon, by-product in FAME obtaining process. Microalgae were supplementary stressed to increase the lipid productivity, by reducing the inorganic nitrogen and partially replacing it with organic nitrogen (hydrolyzed proteins from the same microalgae). Since algal oil has high free fatty acids (FFA) content, a two-step process for FAME synthesis was necessary. In the first step, FFA was esterified with methanol over SO42-/TiO2-La2O3 solid acid catalyst. The second step, i.e. methanolysis of pre-treated oil, was performed over Na2SiO3/Mg-Al-hydrotalcite (Na2SiO3/Mg-Al-HTC) heterogeneous base catalyst. The Na2SiO3/Mg-Al-HTC catalyst was synthesized and then characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), textural analysis (BET method), scanning electron microscopy (SEM), energy dispersive X-ray fluorescence analysis (EDXRF) and Fourier transform infrared (FTIR) spectroscopy. The influences of catalyst loading and stability, methanol-to-oil molar ratio and the reaction time on the FAME yield were carefully studied. FAME producing technology was investigated first in batch and then in a continuous flow process. (C) 2016 Elsevier Ltd. All rights reserved.