Collaborative Proposal: Elucidation and Evaluation of Strategies to Mitigate Secondary Reactions in Cellulose Pyrolysis for Enhanced Production of Hydrolysable Anhydrosugars

摘要：利用森林和农业废弃物生产糖类是生产替代石油的生物燃料和生化产品的关键步骤。一种方法是使用一种叫做热解的古老技术。这只需要加热这种生物质。当纤维素（植物细胞组织的主要成分之一）在真空下快速加热300至600摄氏度（快速热解）时，有可能将其转化为几乎95%的糖，这些糖可以很容易地升级为生物燃料和生物化学物质。用这种方法获得的糖的数量与其他发达的、更昂贵的方法如酶水解相当。不幸的是，当生物质在商业快速热解反应器中在常压下快速加热时，糖的产量远低于使用真空时。事实上，我们通常只看到不到20%的原始纤维素。常压下糖产量的下降是由于植物细胞壁快速热解过程中发生的次级反应引起的。在这个建议中，我们将结合实验室实验和计算机建模工具来了解在大气压下获得的糖量低的原因。提出了新的实用策略，在快速热解过程中大幅增加糖的产量，从而降低来自可再生生物质资源的生物燃料的价格。本提案的主要实际目标是更好地理解中间热解液相低聚糖（纤维素生物糖，纤维素三糖，？）的作用，这些糖通常通过不希望的脱水，交联和缩聚二次反应而丢失。我们将结合创新的实验和动力学建模工具，以更好地理解这些二次反应和酸的机制，例如，减轻一些与木质纤维素基质（或其产物）的不良相互作用。微爆炸增强剂（发泡剂）将被评估促进无水糖雾化，以减少在热解液体中间体中的停留时间，以及在热解反应器内发生不良二次反应的可能性。我们将通过与沃拉-沃拉社区学院（WWCC）合作，开发和评估生物能源运营和可再生资源回收运营副学士学位课程，扩大我们的影响。我们将组织研究生、博士后研究人员和WWCC学生之间的年度研讨会，交流思想，鼓励WWCC学生继续他们的专业发展。本项目也将作为电气工程本科学生进行高级设计项目的平台，构建和改进新型真空运行的金属丝网快速热解反应器。该项目的成果将被纳入西北大学的动力学和反应工程研究生课程以及华盛顿州立大学的生物质热化学转化课程。布罗德贝尔特教授将参加一个培养女孩对科学和工程兴趣的项目。华盛顿州立大学和西北大学的联合合作将在未来产生跨机构的协同效应。

1434073 (Garcia-Perez), 1435228 (Broadbelt)Title: Elucidation and Evaluation of Strategies to Mitigate Secondary Reactions in Cellulose Pyrolysis for Enhanced production of Hydrolysable Anhydrosugars Abstract: The production of sugars from forest and agricultural wastes is a critical step for making bio-fuels and bio-chemicals to replace petroleum. One way to do this is by using an ancient technique called ?pyrolysis?, which simply involves heating up this biomass. When cellulose (one of the main components in plant cell tissues) is heated very fast between 300 and 600 oC (fast pyrolysis) under vacuum it is possible to convert almost 95 % of it into sugars that can be easily upgraded into bio-fuels and bio-chemicals. The quantity of sugars obtained with this process is comparable to other well-developed, more expensive methods like enzymatic hydrolysis. Unfortunately, when the biomass is heated very fast at atmospheric pressure in commercial fast pyrolysis reactors, the production of sugars is much lower than when using vacuum. In fact, we typically see less than 20 % of the original cellulose. The decreased sugar yield at atmospheric pressure is due to very poorly understood secondary reactions that happen during fast pyrolysis on plant cell walls. In this proposal we will combine laboratory experiments and computer modeling tools to understand the reasons for the low quantities of sugars obtained at atmospheric pressure. New practical strategies are proposed to dramatically increase the production of sugars during fast pyrolysis and in this way reduce the price of bio-fuels derived from our renewable biomass resources. The main practical goal of this proposal is to better understand the role of intermediate pyrolysis liquid phase oligomeric sugars (cellobiosan, cellotriosan,?) that typically are lost through undesirable dehydration, cross-linking, and polycondensation secondary reactions. We will combine innovative experimental and kinetic modeling tools to better understand these secondary reactions and the mechanisms by which acids, for example, mitigate some of the undesirable interactions with the lignocellulosic matrix (or their products). Micro-explosion enhancers (blowing agents) will be evaluated to promote anhydrosugar aerosolization to decrease residence time in the pyrolytic liquid intermediate as well as the probability for undesirable secondary reactions to occur inside the pyrolysis reactor. We will broaden our impact by working with Walla-Walla Community College (WWCC) in the development and evaluation of courses for associate degrees in Bioenergy Operations and in Renewable Resource Recovery Operations. We will organize an annual workshop between our graduate students, postdoctoral researchers and WWCC students to exchange ideas and encourage WWCC students to continue their professional development. This project will also serve as a platform for undergraduate electrical engineering students to conduct their Senior Design Project constructing and improving new wire mesh fast pyrolysis reactors capable of vacuum operation. Results from this project will be incorporated into lectures in graduate-level courses on kinetics and reaction engineering at Northwestern University and on biomass thermochemical conversion at Washington State University. Prof. Broadbelt will participate in a program to interest girls in science and engineering. Joint collaboration between WSU and Northwestern University will yield cross-institutional synergy in the future.