General Properties
Pyrolysis-Oils usually are dark brown liquids with a characteristic
odour, remembering the smell of campfire or smokehouses. Unlike liquid fossil energy
sources, Pyrolysis-Oils are hydrophilic and therefore mixable with water up to a
proportion of 35 %. At higher percentages the Bio-Oil separates into an aqueous and
a tarry fraction. The normal content of water, which results as from the residual
moisture of wood as from the thermolytic decomposition, ranges between 20 and 30 %.
Some properties of Pyrolysis-Oils are listed in table 1.
| Properties | Valores médios |
| Content of water | 20-35 % |
| pH | 2-3 |
| Density | 1,2 g/cm3 |
| Carbon | 56 % |
| Hydrogen | 7 % |
| Oxygen | 37 % |
| Nitrogen | 0,1 |
| Viscosities (40°C, 20 % H2O) | 40-100 cP |
| Particles | <0,3 % |
| Net calorific value | 16-18 MJ/kg |
Table 1: typical properties of pyrolysis oils |
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Considering the chemical characteristics, Pyrolysis-Oils consist of various organic, oxygen-containing molecules, principally of carboxylic acids, phenols, lactones, alcohols, furans, aldehydes, ketones and anhydrosugars. By gas chromatography, approximately 200 monomeric substances can be detected. Furthermore, there are oligomeric lignin-derived molecules dissolved in Bio-Oil.