Unconventional Relationships for Hemicellulose Hydrolysis and Subsequent Cellulose Digestion

Cellulosic biomass can be pretreated with dilute sulfuric acid to recover high yields of sugars directly from hemicellulose and subsequently by enzymatic hydrolysis of the residual cellulose, and these sugars can be used to produce fuels and chemicals with unique and powerful economic, environmental, and strategic benefits. Pretreatment is costly for such biological routes, and we seek to better understand hydrolysis kinetics to support emerging applications and needed technology advances. Hemicellulose removal is affected by solids concentration and flow through the solids, contrary to customary first-order reaction models. We also measure a wide range of oligomer species, particularly at lower acid levels, that most kinetic models ignore or oversimplify, and a model is proposed to more accurately predict their behavior. The solubility of oligomers is also being measured by a new technique to better understand its effect on kinetics. New data suggests that lignin alterations during hemicellulose hydrolysis are important in improving enzymatic hydrolysis of cellulose.