Influence of industrial alcohol and additive combination on the physicochemical characteristics of bio-oil from fast pyrolysis of pine sawdust in a fluidized bed reactor with hot vapor filter

Effects of different mass fractions of industrial alcohol additive (10% and 20%) and additive combination (ethanol: 6.58%, acetonitrile: 1.00%, methyl acetate: 2.42%) on the physicochemical characteristics of pine sawdust bio-oil aging for three months by fast pyrolysis of 1-5 kg/h bench-scale fluidized bed reactor with hot vapor filter were investigated. The results indicated that addition of industrial alcohol and additive combination had a significant effect on improving the physicochemical characterization of bio-oil. The additives could significantly lower the viscosity and instantly increase pH value of the bio-oil remarkably and also delay the aging rates of the bio-oil. Results showed that compared with the blank (bio-oil without additive), the pH values of the bio-oils with 10% industrial alcohol (10% IA bio-oil), 20% industrial alcohol (20% IA bio-oil), and additive combination (AC bio-oil) were immediately increased by 12%, 12%, and 21%, respectively when the additives were added. After stored for 90 days, viscosities of crude bio-oil, 10% IA bio-oil, 20% IA bio-oil and AC bio-oil were increased by 200%, 54%, 69%, and 62%, respectively. Two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOFMS) analysis indicated that the aged bio-oil after 90 days storage had a lower levels of phenols than that of the crude bio-oil and the contents of ketones and esters were increased. FT-IR analysis demonstrated that the structures of non-volatile residue of bio-oils were changed and polymerization occurred with other compounds such as alcohols and aldehydes during storage.