We have characterized biotar generated from gasification of wood pellets by infrared spectroscopy (IR), mass spectrometry (MS) and nuclear magnet resonance spectroscopy (NMR). The biomass gasification involves partial oxidation of wood pellets with a product mixture of hydrogen, carbon monoxide, carbon dioxide, methane and small amounts of higher hydrocarbons. Variable amounts of tary materials as well as wood ash are also generated depending on the pyrolysis conditions and catalysts. When the tarry material is coated on the interior of the condenser, polar solvents, such as acetone, are required to clean it. The organic liquid collected from the condenser is a dark brown, gummy material with a strong odor. We analyzed the material coming out of the condenser at the bottom of the cracker.  The elemental analysis of a biotar generated under nitrogen gives a result of 74.3% carbon, 6.24% hydrogen, 0.35% nitrogen, 19.1% oxygen and 0.05% sulfur. The same biotar was analyzed by Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) using negative ion electrospray ionization (-ESI). The majority of components are oxygenates with double-bond equivalence (DBE) versus carbon number distribution of O1 � O7 along a diagonal line, indicating a polymeric nature to these oxygenates.  The differential IR analysis of tarry material on char extracted by CH2Cl2 shows richness of aromatic moiety as phenyl rings, OH-stretching, carbonyl functionalities and ether linkages.  13C NMR shows nearly 70-80% of the carbons from biotars are aromatic. The aromatic region contains considerable amounts (20%) of phenolic components. Alkyl carbons represent the rest of the organic carbon (20-30%), along with smaller amounts of carbonyl/carboxyl groups. The results of the 1H NMR spectroscopy are consistent with that of 13C NMR, where aromatic and benzylic protons dominated the spectrum.

Characterization of biotar from gasification/pyrolysis of mixed wood pellets

243rd National Meeting (2012)

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