Fractionation of processed spruce wood obtained in the production of ethanol

Journal article, 2009

Fuel ethanol can be produced from pretreated spruce wood through enzymatic hydrolysis and fermentation. Processed spruce wood samples (acid-catalyzed steam hydrolysis followed by enzymatic hydrolysis and fermentation) were fractionated into water-soluble products and residual solids. The dioxane/water soluble portions of the solids were fractionated by liquid-liquid extraction. A substantial portion of the processed wood (20-70 %) was insoluble in both water and dioxane/water. An almost pure lignin fraction, corresponding to about 20 % of the total lignin of the wood, was isolated. Examinations by 1H NMR spectroscopy showed that the processes led to extensive cleavage of arylglycerol ß-aryl ethers in the lignin. The lignin content of other fractions could be estimated very roughly by IR spectroscopy. Purified lignin from SO2-catalyzed steam hydrolysis contained approx. 0.2 % sulphur.