Abstract
Wood tar is obtained as a by-product in Eucalyptus carbonization activities in Brazil. Efforts have been made to upgrade this raw material as source of fine chemicals and a precursor for polymeric materials. The distillation process of wood tar has been done on laboratory, pilot-plant and industrial scales. The first step in Eucalyptus tar distillation yields 20% of a watery phase, 30% of crude oil and 50% of pitch (bio-pitch).
The physico-chemical characterization of bio-pitch, obtained as a fusible distillation residue, is being carried out. The results show that bio-pitches are different from coal tar pitches, with lower aromaticity (C=64–75%, H=5.9–6.4%, N=0.4–1.3%, O= 20.7–29.3%) and have infrared absorptions, similar to lignin. 1H NMR and 13C NMR in solution and 13C in the solid state give peaks representative of syringyl and guaiacyl units.
The softening point can be correlated with molecular weight and assumes values of 85–120 °C. The acetone insoluble contents (A.I = 2%, for crude pitch) and HRSEC results indicated that bio-pitches contain macromolecular structures. HRSEC using polystyrene standards and tetrahydrofuran (THF) as solvent indicate an average molecular weight of 2000–5000 daltons, depending on distillation conditions. Bio-pitches show thermoplastic behaviour. A conceptual model of the macromolecular network is proposed.
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Pasa, V.M.D., Carazza, F., Otani, C. (1997). Wood Tar Pitch: Analysis and Conceptual Model of its Structure. In: Bridgwater, A.V., Boocock, D.G.B. (eds) Developments in Thermochemical Biomass Conversion. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-1559-6_35
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DOI: https://doi.org/10.1007/978-94-009-1559-6_35
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