Fast pyrolysis of rice husk under vacuum conditions to produce levoglucosan

Levoglucosan (LG)-enriched pyrolytic oils were obtained from rice husk by lab-scale fast pyrolysis under vacuum conditions. We studied the effect of the pyrolysis temperature (300-700 degrees C) and the pretreatment of the biomass, on the pyrolysis product yields and the selectivity for LG formation. The maximum oil yield (47 wt.%) was obtained from hydrochloric acid-leached rice husk at 400 degrees C, producing 1.4 times more than the amount of oil produced from untreated rice husk at the same temperature. Anhydrosugars were the predominant compounds found in bio-oils under all conditions assessed, LG being the main product. Depending on the pyrolysis conditions, LG concentration was between 9-30 wt.% considering the bio-oil mass, and between 4-60 wt.% considering the initial cellulose mass. H-1 NMR experiments were carried out as an alternative and simple technique to directly determine the amount of LG in bio-oils.

Automated summary

Experimental results showed that the highest oil yield was obtained from hydrochloric acid-leached rice husk at 400 degrees Celsius, with the main product being Levoglucosan (LG).