Interaction of heating rate and N2 atmosphere on bio-oil composition derived from distinct tropical woods

Pyrolysis converts biomass into charcoal, bio-oil, and gases, with product quality dictated by operational conditions. This study investigates the influence of heating rates and N2 atmospheres on the pyrolysis of Eucalyptus urophylla and Licaria sp., which exhibit contrasting lignin contents (24.21% and 35.30%, respectively). Experiments were conducted using slow (6 °C/min) and intermediate (60 °C/min) heating regimes, in the presence and absence of N2 flow (0.40 L/min). The yields were determined, and the bio-oil was fractionated into tar, which was subsequently analyzed by Size Exclusion Chromatography (SEC), Gas Chromatography (GC), and Gas Chromatography coupled with Mass Spectrometry (GC/MS). The bio-oil yields were primarily driven by species composition. Results indicated that E. urophylla produced 41.6% higher bio-oil yields than Licaria sp., showing a significant negative correlation between lignin content and bio-oil generation. The N2 flow modulated the product distribution between species. SEC analysis revealed that slow pyrolysis resulted in a 20–30% increase in the proportion of smaller molecular weight species in the tar compared to the intermediate heating regime. Furthermore, GC/MS analysis identified 12 key lignin-derived phenolic components in the tar. In conclusion, pyrolysis parameters modify the bio-oil composition, enabling the control of molecular size distribution and the specific chemical profile.