CAREER: Revealing Kinetic Pathways by Pulsed-Film Pyrolysis of Cellulosic Biomass

通过燃烧、热解或气化转化木质纤维素、非食品生物质为生产第二代生物燃料提供了一套可持续的技术，这对能源独立、经济增长、全球排放和我们的社会都有重大影响。然而，尽管在过去的几十年里进行了深入的研究，仍然缺乏有关这些系统的基本知识，包括反应途径，中间体和详细的动力学。正是这类信息导致了炼油工业在过去世纪的成功发展，并且是生物质利用所迫切需要的。在对这些转化技术的基本认识方面缺乏进展，部分原因在于原材料的多相性和多尺度性，以及与输送效应错综复杂的大型反应网络的相关复杂性。我们在这项研究中的目标是通过开发和利用一种新的实验技术来开发纤维素热解的单个分子反应的第一个动力学描述被称为？脉冲膜热解，？或亲民党所提出的PFP技术旨在将纤维素的微尺度膜快速加热至400-600 °C，随后等温热解发生限定的时间增量（例如10 ms），然后快速热淬灭。反应速率的动力学信息将通过表征每个连续热脉冲产生的化学物质的数量和类型来获得。研究计划1）。开发脉冲膜热解技术：三个任务将集中在设计，构建和测试纤维素热解的脉冲膜技术。利用多物理场设计模型和新型反应堆结构将允许第一个实验系统能够在高温下进行无输运动力学实验。分为两个具体目标：2。测量纤维素热解的动力学：三项任务将测量初级产物（如左旋葡聚糖和呋喃）的形成速率、左旋葡聚糖的次级反应以及将纤维素还原为活性低聚物的凝相反应。在完成这两个目标后，预计将首次测量纤维素热解主要途径的动力学。智力优点：这项研究将改变我们对固体和凝相生物质化学反应机理和动力学的理解。这项研究的一个引人注目的方面是，它提供了第一个实验测量与关键热解产物形成相关的活化能的策略，可以与正在进行的计算进行比较，以首次阐明生物质热解的机制。生物质反应途径和动力学的科学发现将为构建第一个生物质反应器提供关键数据。原理动力学模型，可用于优化热解反应器。改进的生物质工艺通过以较低的成本生产更高质量的生物燃料和减少对环境的影响，对该国产生了广泛的影响。此外，拟议的生物质热解研究的发现和基本见解将为开发指导材料提供大量机会，以教育未来的本科生，高中生和公众了解生物质转化为燃料和化学品的价值和环境影响。我们建议制定一个综合的战略，具有广泛的影响，结合高中教师的教育和本科生的教学，开发演示文稿的公共研讨会上的主题生物质技术，环境影响和政策。已经提出了举办公共研讨会的逐年发展计划，这些研讨会将与教育材料一起沿着在互联网上播放，以便广泛传播。与专题讨论会相结合的将是一门以可再生能源为重点的本科课程，以及一项NSF-RET提案，该提案旨在为少数民族高度集中的学校（马萨诸塞州斯普林菲尔德、威斯康星州密尔沃基）的科学教师提供服务，并为K-12学生开发学习模块。我们的教育方法将有助于确保来自经济不景气背景和代表性不足的少数民族的学生有机会获得工程科学和技术的鼓舞人心的例子，并使公众充分了解生物质转化的重要性，作为实现独立于进口石油的国家目标的可持续和环境友好的手段。

The conversion of lignocellulosic, non-food biomass by combustion, pyrolysis, or gasification provides a sustainable set of technologies for the production of second generation biofuels that can have significant impact on energy independence, economic growth, global emissions, and our society. However, despite intensive research for the past several decades, there is still a lack of fundamental knowledge pertaining to these systems including reaction pathways, intermediates, and detailed kinetics. It is this kind of information that has led to the successful development of the refinery industry in the past century and which is critically needed for biomass utilization. The lack of progress on fundamental understanding of these conversion technologies is partially rooted in the multiphase and multi-scale nature of the raw material and the associated complexity of a large reaction network convoluted with transport effects.Intellectual Merit: Our objective in this research is to develop the first kinetic description of the individual molecular reactions of cellulose pyrolysis by developing and utilizing a novel experimental technique referred to as ?pulsed-film pyrolysis,? or PFP. The proposed PFP technique aims to rapidly heat micro-scale films of cellulose to 400-600 °C, whereupon isothermal pyrolysis occurs for a defined increment of time (e.g. 10 ms), followed by rapid thermal quench. Kinetic information on the rate of reaction will then be obtained from characterizing the quantity and type of chemical species produced for each consecutive thermal pulse. The research plan1.) Develop the technique of pulsed-film pyrolysis: Three tasks will focus on designing, constructing, and testing the pulsed-film technique for cellulose pyrolysis. Utilization of multi-physics design models and novel reactor construction will allow for the first experimental system capable of transport-free kinetic experiments at high temperature. is divided into two specific aims:2.) Measure the kinetics of cellulose pyrolysis: Three tasks will measure rates of formation of primary products (e.g. levoglucosan and furans), secondary reactions of levoglucosan, and condensed-phase reactions to reduce cellulose to reactive oligomers.At the completion of these two aims, it is anticipated that the kinetics of the major pathways of cellulose pyrolysis will be measured for the first time. Intellectual merit: The proposed research will transformour understanding of the reaction mechanisms and kinetics of solid and condensed-phase biomass chemistry. A compelling aspect of this research is that it provides the first strategy for experimentally measuring the activation energies associated with the formation of key pyrolysis products, which can be compared with ongoing computations to elucidate for the first time the mechanisms of biomass pyrolysis.Broader Impact: The scientific discoveries of biomass reaction pathways and kinetics will provide the critical data for constructing first-principles kinetic models which can be used to optimize pyrolysis reactors. Improved biomass processes broadly impact the country by producing higher quality biofuels with lower cost and reduced environmental impact. Additionally, the discoveries and fundamental insights from the proposed research on the pyrolysis of biomass will provide a plethora of opportunities for developing instructive material to educate prospective undergraduates, high school students and the general public on the value and environmental impact of biomass conversion to fuels and chemicals. We propose to develop an integrated strategy with broad impact which combines the education of high school teachers and the instruction of undergraduates to develop presentations for public symposia on the topic of biomass technology, environmental impact and policy. A year-to-year development plan has been proposed for conducting public symposia, which will be broadcast on the internet along with educational materials for broad dissemination. Integrated with the symposia will be an undergraduate course focused on renewable energy as well as an NSF-RET proposal for hosting science teachers and developing learning modules for K-12 students in schools with high concentration of underrepresented minorities (Springfield, MA, & Milwaukee, WI). Our approach to education will contribute to ensuring that students from economically depressed backgrounds and underrepresented minorities have access to inspiring examples of engineering science and technology and that the general public is well-informed on the importance of biomass conversion as a sustainable and environmentally-friendly means of achieving the national goal of independence from imported oil.