Conversion of Biomass into High-Quality Bio-oils by Degradative Solvent Extraction Combined with Subsequent Pyrolysis

The rapid depletion of fossil fuels has attracted more attention being geared toward the fast pyrolysis Of biomass to produce bio-oils. However, the produced bio-oils usually contain high water, oxygen, and acid contents and low calorific values, which have limited their wide application. Therefore, in this study, a novel two-stage method combining degradative solvent extraction with subsequent pyrolysis was proposed to improve the quality of derived bio-oils. The raw biomass was initially dewatered and deoxygenated using a degradative solvent extraction method to obtain a low-molecular-weight extract (named Soluble). The Solubles were then pyrolyzed at 500 degrees C to prepare bio-oils. The carbon contents and calorific values of bio-oils produced from the Solubles were as high as 90.09% and 44.63 MJ/kg, respectively, which were 1.5-2.0 times higher than those from the raw biomasses. In addition, the water and oxygen contents of bio-oils from the Solubles were significantly lower than the,bio-oils from the raw biomasses. Furthermore, the bio-oils from the Solubles contained much fewer corrosive and reactive acids and more value-added aromatic hydrocarbons compared to those from raw biomasses. In summary, the quality of the bio-oils produced from the Solubles was obviously superior to the bio-oils from the direct pyrolysis of the row biomasses It was shown that degradative solvent extraction combined with subsequent pyrolysis is an effective method to convert raw biomasses into high-quality bio-oils.