In order to convert cellulosic biomass to raw materials for alcohol fermentation, cellulose and a chinquapin, a hard wood, were hydrothermolyzed with hot compressed water in a batch reactor at temperatures between 250 and 405°C.
Cellulose was quickly solubilized to water, and nearly 40% of cellulose could be sac-charified to hexose by adjusting the heating time in the range of 13-30s at the heating temperature of 305-405°C. As a result of fermentation test of the water soluble frac-tion, the fermentation rate was found to be remarkably improved by removing furfurals in the solution through an active carbon treatment, and further, good mass balance was confirmed between the consumed hexose and formed ethanol.
In the case of chinquapin, the hydrothermolysis started at lower temperature than pure cellulse. Active lignin was first decomposed, and then hemicellulose followed by cellulose was hydrolyzed to water solubles (WS), although stable lignin was hard to de-compose and remained as solid residue (methanol insolubles, MI). An increase in the heating temperature caused the decrease in the yield of MI, but did not the increase in the yield of WS because of the second decomposition of WS. However, the WS includ-ing over 20% of hexose was obtained in the yield of near 30% by optimizing the heating time. Since species from lignin were obtained as methanol solubles separately from WS, the WS were suitable for the fermentation and ethanol was successfully produced with saccharomyces.
