Temporal Resolution in Fast Pyrolysis of Lignocellulosic Biomass

主要调查者：李永进编号：1438004植物生物质是生产生物燃料的原料。将植物生物质加工成液体运输燃料的一种方法是在没有空气的情况下快速加热固体生物质材料，这一过程称为热解。热解引发一系列复杂的分解反应，生成液态碳氢化合物、气体和富碳焦炭的复杂混合物。本研究项目将使用一种新的仪器来实时研究复杂的热解反应，并在反应时间不到一秒的情况下非常准确地测量热解产物。根据这些基本信息，将建立详细的反应模型，这些模型可用于改善热解生产液态烃燃料的性能，指导化学反应器的设计和放大，并加速导致商业化的工艺开发。通过该项目提供的教育和扩大参与活动的特点是为中学科学教师开设了一个关于生物可再生能源和生物经济学主题的暑期学院。技术说明热解是将生物质转化为碳氢液体、气体和富碳焦炭的复杂混合物的过程，其中固体生物质材料在没有空气的情况下被快速加热，以启动一系列热分解反应。本项目的目标是实时研究木质纤维生物质快速热解过程中的产物分布。这项研究将由一种独特的微型反应器实现，在这种反应器中，一台快速扫描的高分辨率质谱仪连接到滴管式微炉热解器上。这种配置能够以亚秒级的时间分辨率监测每个分子产品的命运。这项研究将表征葡萄糖碳水化合物快速热解的分子动力学，研究纤维素热解的熔相和传导效应，并探索高时间分辨率的木质素热解。假设纤维素的热解有两个不同的时间阶段，一个是窄时间剖面，另一个是宽时间剖面，分别归因于固体表面热解和熔体热解。纤维素和木质素在极薄薄膜上的纯反应动力学可以忽略不计的熔相反应。通过系统地研究不同链长和糖苷键类型的葡萄糖碳水化合物的热解，将进一步探索纤维素热解过程中基本化学反应的细节。为了监测从等温动力学到传导受限动力学的转变，将研究大范围的薄膜厚度。这也将揭示熔融相热解是如何受到样品大小的影响以及它如何对最终产品分布做出贡献。通过该项目提供的教育和扩大参与活动包括由NSF生物可再生化学品工程研究中心(CBiRC)和爱荷华州立大学NSF EPSCoR计划赞助的关于生物可再生能源和生物经济的中学科学教师暑期学院。该项目将支持并密切合作其中一名参与教师准备有关生物油的课堂材料。大学生和高中生将通过这个项目接触到生物可再生能源技术，包括科学方向项目中代表性不足的少数族裔学生。

Principal Investigator: Young-Jin LeeNumber: 1438004Biomass from plants is a feedstock for the production of biofuels. One route for processing plant biomass into liquid transportation fuels is to rapidly heat up the solid biomass material in the absence of air, a process called pyrolysis. Pyrolysis initiaties a series of complicated decomposition reactions to produce a complex mixture of liquid hydrocarbons, gases, and carbon-rich char. This research project will use a novel apparatus to study the complicated reactions of pyrolysis in real time and measure pyrolysis products very accurately at reaction times of under one second. From this fundamental information, detailed reaction models will be developed, which can be used to improve the performance of pyrolysis processes to produce liquid hydrocarbon fuels, guide chemical reactor design and scale-up, and accellerate process development leading to commercialization. Education and broadening participation activities provided through this project feature a summer academy for middle school science teachers on the subject of biorenewables and the bioeconomy.Technical DescriptionPyrolysis is a process for conversion of biomass to a complex mixture of hydrocarbon liquids, gases, and carbon-rich char where solid biomass material is rapidly heated in the absence of air to initiate a series of thermal decomposition reactions. The goal of this project is to study the product distribution in fast pyrolysis of lignocellulosic biomass in real time. This research will be enabled by a unique micro reactor where a fast-scanning, high-resolution mass spectrometer is attached to a drop-tube micro-furnace pyrolyzer. This configuration is capable of monitoring the fate of each molecular product with sub-second temporal resolution. The research will characterize the molecular kinetics for fast pyrolysis of glucose-based carbohydrates, investigate molten phase and conduction effect in cellulose pyrolysis, and explore lignin pyrolysis in high temporal resolution. It is hypothesized that cellulose pyrolysis occurs in two distinct time steps, one narrow-time profile and one broad profile, which are attributed to solid surface pyrolysis and molten phase pyrolysis, respectively. The pure reaction kinetics of cellulose and lignin pyrolysis on extremely thin film where molten phase reaction is can be ignored will be investigated. Details of elementary chemical reactions in cellulose pyrolysis will be further explored by systematically studying the pyrolysis of glucose-based carbohydrates for various chain lengths and glycosidic bondage types. A wide range of film thicknesses will be studied in order to monitor the transition from isothermal kinetics to conduction-limited kinetics. This will also reveal how molten phase pyrolysis is influenced by sample size and how it contributes to the final product distributions.Education and broadening participation activities provided through this project feature a summer academy for middle school science teachers on the subject of biorenewables and the bioeconomy, sponsored by the NSF Engineering Research Center for Biorenewable Chemicals (CBiRC) and the NSF EPSCoR program at Iowa State University. This project will support and closely collaborate with one of the participating teachers in the preparation of classroom materials about bio-oils. College and high school students will be exposed to the biorenewables technology through this project, including under-represented minority students in Science Bound program.