No abstract

No abstract

In the present study, pyrolysis of corn stover lignin was investigated by using a micro-pyrolyzer coupled with a GC-MS/FID (FID=flame ionization detector). The system has pyrolysis-vapor residence times of 15-20 ms, thus providing a regime of minimal secondary reactions. The primary pyrolysis product distribution obtained from lignin is reported. Over 84 % mass balance and almost complete closure on carbon balance is achieved. In another set of experiments, the pyrolysis vapors emerging from the micro-pyrolyzer are condensed to obtain lignin-derived bio-oil. The chemical composition of the bio-oil is analyzed by using GC-MS and gel permeation chromatography techniques. The comparison between results of two sets of experiments indicates that monomeric compounds are the primary pyrolysis products of lignin, which recombine after primary pyrolysis to produce oligomeric compounds. Further, the effect of minerals (NaCl, KCl, MgCl(2), and CaCl(2)) and temperature on the primary pyrolysis product distribution is investigated. The study provides insights into the fundamental mechanisms of lignin pyrolysis and a basis for developing more descriptive models of biomass pyrolysis.

Hemicellulose is one of the major constituents of biomass. Surprisingly, only very limited information regarding its product distribution under fast pyrolysis conditions is available in the literature. In the present study, a combination of several analytical techniques, including micro-pyrolyzer-GC-MS/FID, gas analysis, and capillary electrophoresis, were used to study the primary pyrolysis product distribution of hemicelluloses extracted and purified from switchgrass. A total of 16 products were identified and quantified, which accounted for 85% of the overall mass balance. The pyrolysis behavior of hemicellulose was found to be considerably different than cellulose and was explained on the basis of a proposed mechanism for glycosidic bond cleavage. Further, the effect of minerals and temperature was investigated. The study provides insight into the fast pyrolysis behavior of hemicellulose and provides a basis for developing models that can predict bio-oil composition resulting from overall biomass fast pyrolysis.