Fast Saccharification of Lignocellulosic Biomass under Mild Conditions in the Medium of Concentrated Lithium Bromide

智力价值：无法从木质纤维生物质中释放能量和成本效益高的糖，这是阻碍基于糖平台生产生物燃料和化学品的技术商业成功的瓶颈。为了应对这一挑战，本研究旨在建立一种从木质纤维生物质中低成本生产糖的创新化学工艺。具体来说，在温和的条件下(120~140℃，5-60分钟)，生物质如玉米秸秆、柳枝花、阔叶木和软木在浓溴化锂(LiBr60%w/w)中直接水解和分馏，在少量酸的催化下进行。生物质中的纤维素和半纤维素被迅速和完全地水解成单体糖(己糖和戊糖)，这些单体糖可以通过生物或化学方法转化为生物燃料和化学品。用过的溴化锂可以通过离子交换树脂、溶剂萃取或结晶从糖中分离出来，并在工艺中重复使用。当纤维素和半纤维素溶解时，木质素以不溶性残留物的形式被分离出来。该木质素有望在联产开发方面具有良好的潜力。预计该工艺可以显著降低木质纤维素制糖的成本，从而促进以糖为基础的生物经济。与酸解或酶法糖化等现有工艺相比，溴化锂强化糖化工艺(1)可直接处理小尺寸木屑，节省了粉碎成本和能源；(2)糖化完全，糖降解有限，糖得率高；(3)产生浓缩糖流供下游转化；(4)化学过程快，不需要昂贵的酶；以及(5)实现生物质分馏为糖和木质素，便于生物质成分的利用。广泛影响：除了创新研究计划外，该建议还强调高质量的教育、新知识的开发和传播以及推广活动。拟议工艺的成功将为以低成本和低能源消耗从木质纤维生物质中生产糖提供一种替代方法。我们预计，新工艺将极大地促进从生物质中生产生物燃料、化学品和材料的生物经济，这将减少温室气体排放，消除目前对化石燃料的依赖，促进农村经济，并改善能源和国家安全。拟议的研究涵盖了科学和工程的广泛的基础和应用方面。这将为教学、培训和学习提供一个理想和独特的平台。综合教育计划将面向广泛的学生。除了普通本科生和研究生外，还将特别关注高中生和代表不足的群体的学生，鼓励他们参加关于生物能源的暑期项目。通过在科学期刊上发表研究论文、在会议上发表研究成果、改进课程设置以及为非学术杂志或媒体撰写文章，向学术界、产业界、学生、政府和公众传播新概念、研究成果、创新知识和技术。所有这些都将直接和/或间接造福于生物能源领域的研究、生产、学习、教育和决策领域。

Intellectual Merit: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 hydrolyzedinto 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) candirectly 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.