Margarida Mateus

This work presents the study of Eucalyptus globulus bark and sawdust direct liquefaction. Laboratory scale experiments were carried out to assess the impact of several variables on the reaction yield and the sugar content of the bio-oil. These variables were the biomass type and concentration, the solvent, and the reaction time. The results show that E. globulus sawdust presented the highest yields (>95%), but the highest sugar content after water extraction was obtained for E. globulus bark (~5.5% vs. 1.2% for sawdust). Simultaneously, industrial-scale tests were carried out at the ENERGREEN pilot plant using the same reaction variables, which resulted in reaction yields of nearly 100%. The reagents and raw materials used, as well as the products obtained (bio-oil, reaction condensates, polyols, and sugar phases) were characterized by elemental analysis, infrared spectroscopy, thermogravimetry, and high-performance liquid chromatography with mass spectrometry. The heating value of the bio-oils is higher than the original biomass (higher heating value of E. globulus sawdust bio-oil 29 MJ/kg vs. 19.5 MJ/kg of the original E. globulus sawdust). The analyses of the bio-oils allowed us to identify the presence of high-added-value compounds, such as levulinic acid and furfural. Finally, a study of the accelerated aging of liquefied biomass showed that the biofuel density increases from 1.35 to 1.44 kg/dm3 after 7 days of storage due to the occurrence of repolymerization reactions.