Dilute-Acid Pretreatment of Corn Residues and Short-Rotation Woody Crops

Abstract: As a prerequisite for the enzymatic saccharification or simultaneous saccharification and fermentation process for ethanol synthesis, a dilute-acid pretreatment of the biomass has been shown to be a very effective first step in the yeast-catalyzed bioprocess. Three hardwoods (silver maple, sycamore, and black locust) and two corn residues (cobs and stover) were chosen and subjected to prehydrolysis with dilute sulfuric acid at 140 and 160 °C for reaction times ranging from 5 to 60 min. Although the hemicelluloses from all five samples could be completely hydrolyzed at both 140 and 160 °C, hydrolysis at 160 °C for the woods and stover produced a superior substrate for the cellulase enzyme from Trichoderma reesei, in which > 90% of the cellulose was hydrolyzed by the enzyme. Corn cobs produced an excellent substrate after only 5 min at 140°C. Small amounts of lignin and glucan were also solubilized by the acid in all samples.