Chemical Composition and Reactivity of Oils Derived from Wood Fast Pyrolysis

Fast pyrolysis oils, provided by four different industrial-scale plants, and conventional pyrolysis oils obtained for several heating temperatures, have been characterized by means of GC/MS. About ninety compounds have been identified and forty compounds have been quantified. Apart from water (16-30%), the main contributors of fast pyrolysis oils are: hydroxyacetaldehyde (3-7%), acetic acid (2-5%), levoglucosan (3-4.5%) and hydroxypropanone (1-4%). A reduction in the heating rate (conventional versus fast pyrolysis) enhances the formation of carboxylic acids and water with a diminution in levoglucosan and hydroxyacetaldehyde. Combustion, studied under thermogravimetric conditions, is a two-stage process. The evaporation of the liquid fuel, with homogeneous combustion of released vapors, is followed by the heterogeneous oxidation of secondary char.