Investigation of the relevance between thermal degradation behavior and physicochemical property of cellulose under different torrefaction severities

Abstract Torrefaction pretreatment can upgrade biomass by reducing its oxygen content. In this study, torrefaction pretreatments with different severities (200 °C, 230 °C, 260 °C, and 290 °C) were employed to study their effects on the pyrolysis behaviors and kinetics of cellulose. Results showed that pretreatment at 290 °C was highly effective for oxygen removal. Among the torrefied samples, the solid product of cellulose torrefied at 290 °C had the lowest mass yield of 81.80%, lowest energy yield of 89.60%, highest carbon content of 44.91%, and highest HHV of 16.67 MJ kg−1. Pyrolysis activation energy of torrefied cellulose changed slightly at 200–260 °C, but increased significantly at 290 °C. According to XRD results, at the torrefaction temperature of 290 °C, the crystal structure of cellulose changed significantly. The results of Py-GC/MS showed that the relative contents of anhydrosugars in the bio-oil were decreased by torrefaction pretreatment. The high temperature at 290 °C has the most significant effect on the performance of bio-oil.