Tuesday, April 20, 2010 - 3:30 PM
5-05

Separation, hydrolysis and fermentation of pyrolytic sugars

Jieni Lian1, Shuai Zhou1, Zhouhong Wang1, Chun-zhu Li2, Manuel Garcia-Perez1, and Shulin Chen1. (1) Biological Systems Engineering, Washington State University, LJ Smith 213, Pullman, WA 99163, (2) Curtin Centre for Advanced Energy Science and Engineering, Curtin University of Technology, Perth, 6845, Australia

  Converting the sugar contained in the bio-oil produced from pyrolysis into ethanol can enhance the economic viability of biorefineries. The results in this paper prove that the anhydro-sugars (levoglucosan and cellobiosan) in bio-oils obtained from the fast pyrolysis of lignocellulosic materials can be separated from the phenolic fraction by solvent extraction.  The sugars then can be detoxified and fermented to produce ethanol. The pyrolytic sugars recovered in the aqueous phase were hydrolyzed into glucose using sulfuric acid as catalyst. Toxicological studies showed that the phenols and carboxylic acids were the main species inhibiting the growth of Saccharomyces cerevisiae. Although ethyl acetate proved to be a useful solvent to extract phenols, the distribution coefficient of these compounds in the phases formed (aqueous and ethyl acetate) was not high enough to ensure their complete removal from the aqueous phase in few extraction steps.  The phenols that were not extracted with ethyl acetate were removed by adsorption with Activate Carbon. The sulfuric acid employed to hydrolyze the sugars and the carboxylic acids produced during pyrolysis were neutralized with Ba(OH)2. Based on the fermentation results, inhibition of toxic compounds in the pyrolysis aqueous phase was completely removed, and ethanol yield of more than 0.45 g EtOH/g glucose could be reached.

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