Investigation of representative components of flue gas used as torrefaction pretreatment atmosphere and its effects on fast pyrolysis behaviors

In this study, three torrefaction atmosphere (N₂, CO₂ and 2 vol% O₂ with N₂ balance) were used to study effects of representative main components of flue gas during torrefaction and subsequent pyrolysis. Torrefaction pretreatment was carried out in a fixed-bed reactor at 230 °C and 250 °C, respectively. Results showed after torrefaction, torrefied samples from oxygenated atmosphere presented severer hemicellulose decomposition. And its effects on fast pyrolysis were investigated in thermogravimetry analysis and bench-scale fixed-bed reactor. It was found that oxygenated atmosphere preferred to give higher relative content of phenols at 230 °C and furans at 250 °C. For CO₂, higher relative content of ketones and lowest phenols were got. The result also indicated that it's the O₂ in flue gas which significantly improved the char yield. These results will be beneficial reference to predict and interpret alterations of pyrolysis behaviors when flue gas constitution changes in industrial application.