Effect of in-situ addition of alcohol on yields and properties of bio-oil derived from fast pyrolysis of eucalyptus bark

Production of renewable fuels by blending bio-oil with alcohols and upgrading under supercritical conditions

“…reported that the water reduction is due to the dilution effect of the anhydrous alcohols [18]. After the supercritical alcohol reactions, BM2 exhibited the highest water content.…”

“…One reason for the lower pH in BI2 may be the higher presence of acids in BI2 compared to BM2 and BE2. The acids in the bio-oil were eliminated after reacting with methanol and decreased by 15.88% and 17.44% with after ethanol and isopropanol reaction compared to their respective blends Esterification reactions produce water as a by-product, one of the reasons for the increased water content after reacting the bio-oil with methanol may be the higher esterification activity when reacting the bio-oil with methanol [18,27,30,31]. Methanol treated bio-oil exhibited the highest water and ester content (29.78 wt-%; 29.89 area (%), respectively), followed by ethanol (23.37 wt-%; 27.68 area (%), respectively) and isopropanol (18.87 wt-%; 22.35 area (%), respectively).…”

“…After the supercritical alcohol reactions, BM2 exhibited the highest water content. This is due to esterification reactions of methanol and acids in the bio-oil occurred and generated water as a product [18,30,31]. Another reason for the increased water content after the supercritical methanol reaction compared to the methanol blend may be linked to the high gas yield after the methanol reaction (Table 1).…”

“…Alcohols, such as methanol, ethanol, and isopropanol have been used to blend with bio-oil to increase its homogeneity and reduce its viscosity and the rate of ageing [15][16][17][18][19][20][21][22][23][24][25]. Diebold and Czernik found additives such as methanol and ethanol can drastically reduce the ageing rate of pyrolysis oil [25].…”

“…Moreover, the viscosity of the methanol/oil blend was significantly lower than the untreated bio-oil. Likewise, Pidtasang et al found the addition of methanol or ethanol significantly reduced the bio-oil viscosity (initial bio-oil viscosity 21 to 7 cSt bio-oil/ alcohol blend) [18]. Yu et al found blending methanol or ethanol with bio-oil proved to be a simple and costeffective method for reducing the viscosity and improving homogeneity and stability of the bio-oil [22].…”