CHARACTERIZATION AND STABILITY ANALYSIS OF WOOD-DERIVED BIO-OIL

The stability characteristics of a bio-oil, produced by the high pressure liquefaction of aspen wood were studied by observing the changes in its physical properties, composition and distillation characteristics with time. Distillation characteristics of the fresh bio-oil showed that maximum amount of organic distillate was obtained at 172 Pa and 200-degrees-C. This distillate fraction mainly consisted of aromatic, aliphatic and naphthenic hydrocarbons and oxygenated compounds such as phenols, furans, alcohols, acids, ethers, aldehydes and ketones. The bio-oil viscosity, and chemical composition were found to change substantially over time probably due to polymerization of some components. Upon storage, the concentration of aromatic hydrocarbons and phenols decreased while the concentration of aldehydes and ketones increased. Also, the oxygen content of the distillate decreased from 22.7 wt% for the fresh bio-oil to 18.8 wt% after 31 days. However, when the bio-oil was mixed with tetralin it was observed that the properties of the mixture remained unchanged with time. Tetralin was found to donate hydrogen leading to the improvement in bio-oil stability. A free radical mechanism is proposed to explain the effect of tetralin.