Potencial da Monoraphidium sp. produzida em cultivos outdoor para obtenção de biocombustíveis de terceira geração

Abstract

Microalgae are promising biomasses for obtaining third generation (3G) biofuels, because in addition to accumulating large amounts of lipids that can be converted into biodiesel from transesterification, their residual biomass can be used in other conversion processes. In addition, they have rapid growth, do not compete with food sources, and can be grown on a large scale in outdoor cultivation systems. Therefore, the present work aims to evaluate the potential for the generation of 3G biofuels from biomass of the Monoraphidium sp., obtained from intensive outdoor crops, through the characterization of the lipid extract and its conversion through the flash pyrolysis process. For this, the biomasses were characterized in terms of dry matter, ash, protein, lipids (TL) and carbohydrates content and also through thermogravimetric analysis (TGA / DTG), spectroscopy in the middle infrared (FT-IR) and near (FT-NIR). The ash characterization was carried out through X-ray fluorescence (FRX) and X-ray diffraction (DRX). The lipid extract, obtained by the Schmid-Bondzynski-Ratzlaff method, was evaluated for its fatty profile by gas chromatography coupled to a mass spectrometer (GC-MS). The preliminary characterization results reveal biomasses with high protein content (20.05 - 34.81%), carbohydrates (22.07% -48.44%) and ash (13.02 - 33.29%). As for TL, the results varied between 8 - 22% and showed a fatty acid profile rich in C16: 0, C16: 4 ω3, C18: 2 ω-6, C18: 3 ω-3 and C18: 4 ω -3. Catalytic flash pyrolysis (Py-GC / MS) of biomass before and after extraction and lipid extract was also performed, using zeolite HZSM-5 as a catalyst, which provided an improvement in the characteristics of the products generated in relation to conventional pyrolysis. , promoting an increase in the formation of renewable aromatic hydrocarbons in all three cases. For the lipid extract, a higher formation of alkanes in the C8-C12 range (16.38%) was observed in comparison to what was obtained for the biomass pyrolysis before and after extraction, thus indicating its capacity for generating renewable hydrocarbons that serve as production ranges for biokerosene and mainly biogasoline. It is concluded with these results that Monoraphidium sp. presents the energy potential for the production of 3G biofuels, either through the conversion of oil into biodiesel or the production of renewable fuels from catalytic pyrolysis.