The effect of sugar decomposed on the ethanol fermentation and decomposition reactions of sugars

Abstract

A batch reactor was used to investigate the dilute acid hydrolysis reaction of alpha-cellulose and sugar decomposition reactions. Varying the sulfuric acid concentration from 0.07 to 5.0% for reaction temperatures between 180 and 220°C significantly affected glucose yields, which ranged from about 70% to below 10%. Increasing the reaction temperature enhanced this effect. Similar experimental results were obtained for the decomposition of xylose. For sugar decomposition reactions, less than 0.3 g/L of furfural and 5-hydroxymethylfurfural (5-HMF) were produced from glucose and xylose in the absence of sulfuric acid at 190°C and 15 min of reaction time, but adding a small amount of sulfuric acid (0.5%) dramatically increased the decomposition rate and led to the formation of four undesireable products: formic acid, 5-HMF, acetic acid, and furfural. In both hydrolysis and fermentation reactions formic acid, acetic acid, and 5-HMF severely inhibited ethanol fermentation, while furfural had less of an inhibition effect.