Production of bioethanol: Structural characterization of pretreated lignocellulose

Efficient conversion of lignocellulosic materials to ethanol requires pretreatment and hydrolysis prior to the ethanolic fermentation. This pretreatment renders the biomass more susceptible to the subsequent hydrolysis. Of the wide variety of pretreatment methods presently available, wet oxidation (Bjerre et al., 1996; McGinnis et al., 1983; Schmidt & thomsen, 1997) and steam explosion (puls et al., 1985; Saddler et al., 1993) are among the most promising. However, fermentation of the pretreated hydrolysates with the anaerobic thermophilic bacterium Thermoanaerobacter mathranii strain A3M1, adapted to the hemicellulose hydrolysate, has until now resulted in low ethanol yields, indicating incomplete hydrolyzation or the presence of inhibitory compounds in the hydrolyzate (Ahring et al., 1996; Sommer, 1998). Therefore, a structural study of the hemicellulose fraction is being conducted. This includes investigations of the structure of the hemicellulose fraction prior to pretreatment, prior to hydrolysis, prior to fermentation, and after fermentation. Various techniques, such as gas chromatography / mass spectrometry (GC/MS), size-exclusion chromatography (SEC), and nuclear magnetic resonance spectrometry (NMR), will be used in this study. Preliminary results from these investigations will be presented and discussed.