Effects of torrefaction on yield and quality of pyrolysis char and its application on preparation of activated carbon

The effect of torrefaction on the yield and quality of pyrolysis char and its application on preparation of activated carbon was investigated in this study. In addition, the effect of torrefaction temperature at temperature range between 220 and 280 °C on fuel characteristics was discussed. The results indicated that torrefaction pretreatment improved the fuel characteristics of rice husk samples, and torrefaction had a significant influence on yield and quality of pyrolysis char. With the increase of torrefaction temperature, the yield of pyrolysis char based on dry rice husk samples increased, and the yield of liquid product decreased, while the yield of gas product remained unchanged. It can be seen that torrefaction has little effect on the fuel characteristics of pyrolysis char. However, it has significant effect on internal pore structure of pyrolysis char which can be used as the precursor for preparation of activated carbon. Four kinds of pyrolysis chars obtained from original and torrefied rice husk samples were activated under the same preparation conditions. Torrefaction pretreatment enhanced the yield and quality of activated carbon. The activated carbon obtained from torrefied rice husk samples at the torrefaction temperature of 280 °C exhibited highest specific surface area (2679 m2/g) and pore volume (1.8883 cm3/g), suggesting the potential application as adsorbent.