Effect of Storage Time on the Chemical Characterization of Pyroligneous Liquor From Eucalyptus Wood

Abstract: This research focused on the effect of storage time on the chemical composition of the pyroligneous liquor (PL) produced during the pyrolysis of eucalyptus wood in a laboratory furnace at a relatively low heating rate (1 °C min⁻¹) and a maximum temperature of 400 °C. The chemical compounds present in PL were identified through gas chromatography-mass spectrometry. This analysis was repeated over 19 months to observe changes in PL composition. Compounds such as 1,2-butanediol, 2-methoxytetrahydrofuran, 1,2-cyclopentanedione were only detected in the fresh PL and not after 11 or 19 months of storage. On the other hand, in PL stored for 11 and 19 months, new compounds were found, such as propanoic acid, butanediol, 5,9-dodecadien-2-one,6-10-dimethyl cyclopentanone, which were not observed in fresh PL. This suggests that PL from eucalyptus wood pyrolysis contains reactive compounds, mainly oxygenated, that interact during storage. Regarding the moment of stabilization of the qualitative composition of the PL, this research suggests that it is only reached after 11 months of storage. Phenol and furan derivatives were found to be stable, only reacting in their side chains without affecting the central ring. On the other hand, derivatives of tetrahydrofuran showed significant reactivity and tended to disappear with storage time. Graphical Abstract: [Figure not available: see fulltext.].