8-85: Investigation of a novel pretreatment to realize both high hemicellulose sugar recovery and more digestible cellulose

Dilute sulfuric acid pretreatment is effective in reducing biomass recalcitrance by improving enzyme accessibility to cellulose and consequently increasing sugar release. Because previous research has shown that conditions that maximize individual sugar yields in pretreatment or enzymatic hydrolysis do not usually occur at the same pretreatment conditions as those that maximize total sugar yields from the two steps combined, a novel pretreatment strategy was applied and optimized to maximize total xylose and glucose yields from both pretreatment and enzymatic hydrolysis. We chose switchgrass as the feedstock, because of its obviously different severity values for optimal xylose yields and glucose yields versus total sugar yields.  Pretreatment was performed over a range of temperatures and times with and without acid to determine how sugar yields from each step varied. The resulting solids were then enzymatically hydrolyzed, and pretreatment conditions defined to maximize the release of glucose and xylose from both pretreatment and enzymatic hydrolysis. This approach holds promise to improve overall sugar yields and reduce operating and equipment cost through application of more mild pretreatment conditions that reduce sugar losses while improving digestion of the pretreated solids.