Comparative material balances around pretreatment technologies for the conversion of switchgrass to soluble sugars

• DOI: 10.1016/j.biortech.2011.04.002
• Publication Date: 2011-04-15T21:23:32Z
• Authors: Rebecca J. Garlock; Venkatesh Balan; Bruce E. Dale; V. Ramesh Pallapolu; Y.Y. Lee; Youngmi Kim; Nathan S. Mosier; Michael R. Ladisch; Mark T. Holtzapple; Matthew Falls; Rocio Sierra-Ramirez; Jian Shi; Mirvat A. Ebrik; Tim Redmond; Bin Yang; Charles E. Wyman; Bryon S. Donohoe; Todd B. Vinzant; Richard T. Elander; Bonnie Hames; Steve Thomas; Ryan E. Warner
• Keywords: Xylose; Polymers; Hydrolysis; 0211 other engineering and technologies; 02 engineering and technology; Panicum; 6. Clean water; Glucose; Solubility; Cell Wall; Carbohydrate Metabolism; Biomass; Biotechnology

For this project, six chemical pretreatments were compared for the Consortium for Applied Fundamentals and Innovation (CAFI): ammonia fiber expansion (AFEX), dilute sulfuric acid (DA), lime, liquid hot water (LHW), soaking in aqueous ammonia (SAA), and sulfur dioxide (SO(2)). For each pretreatment, a material balance was analyzed around the pretreatment, optional post-washing step, and enzymatic hydrolysis of Dacotah switchgrass. All pretreatments+enzymatic hydrolysis solubilized over two-thirds of the available glucan and xylan. Lime, post-washed LHW, and SO(2) achieved >83% total glucose yields. Lime, post-washed AFEX, and DA achieved >83% total xylose yields. Alkaline pretreatments, except AFEX, solubilized the most lignin and a portion of the xylan as xylo-oligomers. As pretreatment pH decreased, total solubilized xylan and released monomeric xylose increased. Low temperature-long time or high temperature-short time pretreatments are necessary for high glucose release from late-harvest Dacotah switchgrass but high temperatures may cause xylose degradation.