Inability of energy- and cost-effectively releasing sugars from lignocellulosic biomass is a bottleneck retarding commercial success of the technologies based on the sugar platform for producing biofuels and chemicals. In response to this challenge, this research is to establish an innovative chemical process for low-cost production of sugars from lignocellulosic biomass. Specifically, biomass like corn stover, switchgrass, hardwood, and softwood is directly hydrolyzed and fractionated in concentrated lithium bromide (LiBr, 60% w/w) in presence of small amount of acid as catalyst under mild conditions (120~140ºC, 5-60 min) without any pretreatment. Cellulose and hemicellulose of the biomass are quickly and completely hydrolyzed into monomeric sugars (hexoses and pentoses), which can be converted into biofuels and chemicals biologically or chemically. The used LiBr can be separated from sugars by ionexchange resin, solvent extraction or crystallization and reused in the process. Lignin is separated as insoluble residue when cellulose and hemicellulose are dissolved. The lignin is expected to have a good potential for co-product development. It is anticipated that the process could significantly reduce the production cost of sugars from lignocellulose and therefore promote the sugar-based bioeconomy. Compared with existing technologies, such as acid hydrolysis or enzymatic saccharification, the LiBr-enhanced saccharification process (1) can directly handle small size wood chips and therefore save the cost and energy for size reduction; (2) has a high sugar recovery yield because of complete saccharification and limited sugar degradation; (3) generates a concentrated sugar stream for downstream conversion; (4) is fast chemical process and does not need expensive enzymes; and (5) achieves fractionation of the biomass into sugars and lignin, facilitating utilization of biomass components.
Broader Impacts: In addition to innovative research program, this proposal also emphasizes on high-quality education, development and dissemination of new knowledge, and outreach activities. The success of proposed process would provide an alternative approach for producing sugars from lignocellulosic biomass at low cost and low energy consumption. We anticipate the new process would greatly promote the bioeconomy for producing biofuels, chemicals, and materials from biomass, which could reduce greenhouse gase emission, eliminate current dependent on fossil fuels, promote rural economy, and improve energy and national security. The proposed research covers broad range of fundamental and applied aspects of science and engineering. This would provide an ideal and unique platform for teaching, training and learning. The integrated education plan will target broad range of students. In addition to regular undergraduate and graduate students, special attention will be paid to the students from high school and underrepresented groups by encouraging them participating summer projects on bioenergy. New concepts, research findings, innovative knowledge and technologies will be disseminated to academia, industry, students, government, and the general public through publishing research papers in scientific journals, presenting research outcomes at conferences, enhancing curriculum, and writing articles for non-academic magazine or media. All these will directly and/or indirectly benefit the community of research, production, learning, education, and policy-making in the area of bioenergy.
