Production of Bio-Ethanol from Beech Wood Pellets via Mild Acetone Organosolv Fractionation

Advanced biofuels are produced from renewable resources that comply with stringent sustainability criteria, and lower GHG emissions than fossil fuels. In the BECOOL/BioValue EU-Brazil cooperation project, novel value chains for advanced bioethanol are developed. Second generation (2G) bio-ethanol represents the most important advanced biofuel from sugar streams, but its production costs are higher than those of other fuels, and innovations are needed to improve efficiency and economics of the process. In this work, beech wood pellets were treated using the FABIOLA^TM technology, an acetone-based low-temperature organosolv fractionation process. This fractionation results in three main product streams: lignin, a high-purity cellulosic pulp and hemicellulose sugars in solution. The cellulosic pulp was enzymatically hydrolysed producing a glucose-rich (C6) stream and the hemicellulose sugar solution (C5) is conditioned for further biological conversion. The C6 and C5 streams obtained were used for fermentation by the yeasts Saccharomyces cerevisiae and Spathaspora passalidarum, respectively. While the C6 stream was readily fermentable, the C5 stream was only fermentable after dilution. Therefore the C5 stream was subjected to detoxification by activated carbon. Detoxified C5 streams showed higher fermentability and the production of bio-ethanol reached approximately 0.3 g bio-ethanol/gram xylose consumed. Fermentation experiments at 10-L scale confirmed the results obtained at laboratory scale. Combining FABIOLA^TM and detoxification resulted in efficient C6 and C5 utilization for bio-ethanol production.