Influence of temperature on bamboo torrefaction under carbon dioxide atmosphere

Bamboo was torrefied under carbon dioxide atmosphere at 240-340 degrees C, obtaining solid products with mass yield 40.58-96.89%, energy yield 63.01-99.09%, and higher heating value 18.78-28.51 MJ/kg. The solid products were characterized by FTIR, NMR, TG/DTA, and X-ray diffraction analysis. Under the severest torrefaction condition, cellulose and hemicelluloses were completely decomposed. From the initial bamboo to the heavily torrefied sample, C concentration increased but H and O concentrations decreased. A high temperature of 320 degrees C yielded product having atomic H/C and O/C ratios in the region of lignite, and a higher temperature of 340 degrees C produced torrefied sample with atomic H/C and O/C ratios in the region of coal. The hydrophobicity of torrefied bamboo was increased with the increase of torrefaction temperature. Results indicated that torrefaction under carbon dioxide was a promising process for the utilization of bamboo. (C) 2015 Published by Elsevier B.V.