THE INFLUENCE OF TEMPERATURE AND HEATING RATE ON THE PYROLYSIS OF BIOMASS

The slow pyrolysis of biomass in the form. of pine wood was investigat ed in a static batch reactor at pyrolysis temperatures from 300 to 720 degrees C and heating rates from 5 to 80 K min(-1). The compositions and properties of the derived gases, pyrolytic oils and solid char wer e determined in relation to pyrolysis temperatures and heating rates. In addition, the wood and the major components of the wood-cellulose, hemicellulose and lignin were pyrolysed in a thermogravimetric analyse r (TGA) under the same experimental conditions as in the static batch reactor. The static batch reactor results showed that as the pyrolysis temperature was increased, the percentage mass of solid char decrease d, while gas and oil products increased. There was a small effect of h eating rate on product yield. The lower temperature regime of decompos ition of wood showed that mainly H2O, CO2 and CO were evolved and at t he higher temperature regime, the main decomposition products were oil , H2O, H-2, hydrocarbon gases and lower concentrations of CO and CO2. Fourier transformation infra-red spectroscopy and elemental analysis o f the oils showed they were highly oxygenated. The TGA results for woo d showed two main regimes of weight loss, the lower temperature: regim e could be correlated with the decomposition of hemicellulose and the initial stages of cellulose decomposition whilst the upper temperature regime correlated mainly with the later stages of cellulose decomposi tion. Lignin thermal decomposition occurred throughout the temperature range of pyrolysis. Copyright (C) 1996 Elsevier Science Ltd.