Rice husk pyrolysis polygeneration of levoglucosan-rich bio-oil and functional bio-char: roles of hydrothermal pretreatment and acidic hydrothermal pretreatment on products.

Positive roles of hydrothermal pretreatment and acidic hydrothermal pretreatment were researched in this study. Results of pyrolysis indicated that hydrothermal pretreatment not only significantly enriched levoglucosan (LG) content in bio-oil, but also increased specific surface area of bio-char. When acid was introduced into hydrothermal pretreatment process, the top-quality liquid and solid products acquired at a relatively low pretreatment temperature. For bio-oil, the LG content increased from 0% in rice husk (RH) to 32.68% in the sample hydrothermal pretreated in deionized water at 170 ℃ (TRH170). The highest LG content of 43.0% obtained from the sample hydrothermal pretreated in phosphoric acid solution at 115 ℃ (PTRH115). The BET of bio-char after activation increased from 2135.6 m²/g in RH to 2508.3 m²/g in TRH170. And acid addition optimized the pore distribution of activated bio-char. Both of the average pore size and efficient pore volume in micro-pore section were noticeably increased. [ABSTRACT FROM AUTHOR]