THF: A novel co-solvent pretreatment strategy to achieve high combined sugar yields from lignocellulosic biomass

The recalcitrance of lignocellulosic biomass such as hardwoods, grasses, and agricultural and forestry residues poses the major obstacle to their low cost conversion to fuels and chemicals. For biological conversions, cellulose and hemicellulose accessibility to enzymes and enzyme effectiveness are the main factors limiting sugar yields at the low enzyme loading required for commercial success. Developing effective pretreatment technologies that open up the biomass structure and increase accessibility to enzymes is vital to overcoming biomass recalcitrance as the economic barrier to low cost sustainable transportation fuels. We have found that Tetrahydrofuran (THF) is a low-boiling, aprotic, and moderately polar solvent that can be applied in a one-pot single phase reaction to promote the deconstruction of biomass and extraction of lignin beyond existing pretreatment technologies. In this study, various feedstocks were pretreated in our THF co-solvent system with dilute acid over a range of temperatures and reaction times to determine the extent of lignin removal and overcoming biomass recalcitrance in terms of total sugar release in a combined pretreatment and enzymatic hydrolysis approach. Additional pretreatments using dilute sulfuric acid, hot water, and ethanol (organosolv) were also compared at the same conditions to demonstrate the advantages of our THF co-solvent pretreatment strategy. We will provide detailed evidence in the form of pretreated solids compositions, mass balances, SEM images, and combined sugar release data from different enzyme loadings in our comparisons.