An FT-IR spectroscopic study of carbonyl functionalities in bio-oils

• Published in: Fuel (Guildford) Vol. 90; no. 11; pp. 3417 - 3423
• Main Authors: Lievens, Caroline, Mourant, Daniel, He, Min, Gunawan, Richard, Li, Xiang, Li, Chun-Zhu
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.11.2011; Elsevier
• Subjects: Applied sciences; Bark; Bio-oil; Carbonyl; Carbonyls; Catalysts; Energy; Energy. Thermal use of fuels; Esterification; Exact sciences and technology; FT-IR; Fuels; Infrared spectroscopy; Leaves; Methyl alcohol; Pyrolysis; Spectra; Wood; Pyrolysis; FT-IR; Carbonyl; Esterification; Bio-oil; Lignin; Hemicellulose; Wood; Cellulose; Bark; Ketone; Ester; Upgrading; Tree; Catalyst; Heavy oil; Methanol
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2011.06.001

► Investigation of carbonyl groups in bio-oil with FTIR spectroscopy. ► Concentrations of carbonyl groups in bio-oils vary with biomass feedstock. ► Different esterification reactivities for carbonyl groups in light and heavy bio-oil fractions. Pyrolysis bio-oil contains abundant O-containing structures. Carbonyls are particularly important not only because they are abundant and exist in many forms (e.g. as acids, esters, ketones and aldehydes) but also because they are reactive and are a key consideration of bio-oil upgrading. This study aims to investigate the distribution of carbonyl groups in a variety of bio-oil samples prepared from the pyrolysis of mallee wood, bark and leaves in a fluidised-bed reactor. Some bio-oil samples also underwent esterification reactions with methanol in the presence of solid Amberlyst acid catalyst. The bio-oil samples were diluted with isopropanol prior to the acquisition of FT-IR spectra using a CaF2 liquid cell. The FT-IR spectra of bio-oils in the range of 1490–1850cm−1 were deconvoluted with 9 Gaussian bands. Our results reveal that the bio-oils from the pyrolysis of wood, bark and leaves of the same mallee tree species had very different concentrations and types of carbonyls, which are related to the contents of hemicellulose, cellulose, lignin and extractives in the wood, bark and leaves. Our study also reveals that the carbonyls in the light and heavy fractions of a bio-oil may react differently during the reactions of bio-oil with methanol in the presence of the Amberlyst solid acid catalyst.