High Furfural and Levoglucosan Selectivity from Stepwise Torrefaction and Fast Pyrolysis of Sugarcane Trash Washed with Citric Acid

Converting agricultural waste biomass into value-added chemicals is attractive. However, a low selectivity for target chemicals hinders practical applications. This study presents a stepwise strategy to convert sugarcane trash (ST) into furfural and levoglucosan with high selectivity. The approach includes citric acid washing to reduce mineral content in ST, followed by torrefaction at different temperatures (210 degrees C, 250 degrees C and 290 degrees C) in a tube furnace and then fast pyrolysis at 500 degrees C in a micro -reactor. This study highlights the valorization potential of the torrefaction liquid, an often overlooked by-product from torrefaction, through significantly increasing furfural selectivity during the torrefaction of washed ST. Furthermore, the vapors from subsequent fast pyrolysis of washed-torrefied ST exhibited reduced acetic acid content compared to that of solely washed ST, which is advantageous for minimizing the acidity of the resulting bio-oil. Moreover, fast pyrolysis of ST, treated with washing and torrefaction at 250 degrees C, achieved a high levoglucosan yield while maintaining a high furfural yield obtained in the prior torrefaction step. The findings of this study provide valuable insights into future research and industrial applications in agricultural waste biomass utilization.