UNS: Establishing Elementary Mechanisms of Biomass and Hemicellulose Torrefaction

PI：Phillip R.Westmoreland建议编号：1512401将木质生物质运输到中央处理设施以转化为有用的液体燃料的成本可能很高，特别是在人口稀少的农村地区。热解是将植物生物质的重量和体积降低到更容易运输的形式的过程。在烘烤过程中，收获的生物质在没有空气的情况下在200至300摄氏度的温度下加热，以产生密集的富含生物油的原料。然而，这种材料的特性并不是很好，并且含有各种各样的气体、液体和固体形式的化合物。该项目将开发一个生物质燃烧的综合数学模型，利用详细反应过程的知识来预测能源需求和最终产品混合物。然后，这个模型将被用来开发烘烤过程，这种过程可以被量身定做，从木质生物质中制造出能量密集、低氧的材料。研究成果将被用来在本科和研究生水平的工程课程中提供范例，并通过高中教师的参与，为高中学生开发生物燃料主题的课堂材料。本研究的目标是开发一个综合的模型，用于研究木质生物质半纤维素部分在热解过程中的基本反应和动力学。在热解过程中，生物质在200-300摄氏度的惰性气氛中加热。据推测，周环反应也描述了半纤维素的热解。周环反应是已知的准确描述纤维素热解的反应。该模型将利用反应动力学实验、计算量子化学和反应理论来开发。热重分析将提供热解的瞬时热。产品气体和蒸气将通过二维气相色谱-飞行时间质谱仪(GCxGC-TOFMS)实时分析。这些实验将使用木质生物质(火炬松)、半纤维素生物聚合物木聚糖和半乳甘露聚糖以及半纤维素单体木糖、阿拉伯糖、甘露糖和半乳糖的固体样品进行。生物油产品蒸气的在线GCxGC-TOFMS分析将研究固体闪速热解的反应过程，同时还将利用固体核磁共振(NMR)分析剩余固体结构。对单体热解的量子化学分析有望产生更多的机理见解。完整的模型将预测木质生物质中纤维素和半纤维素部分的反应动力学和产物。基于这项研究的教育活动包括指导本科生工艺设计团队设计热化学生物质加工厂，为本科生和研究生编写反应动力学和运输课程的课程材料，以及为本科生和高中教师提供研究经验。

PI: Phillip R. WestmorelandProposal Number: 1512401The transportation of woody biomass to a central processing facility for conversion into useful liquid fuels can be costly, particularly in sparsely populated rural areas. Torrefaction is process that reduces the weight and volume of plant biomass to a form which can be transported more easily. In torrefaction, harvested biomass is heated in the absence of air at 200 to 300 degrees Celsius to create a dense bio-oil rich feedstock. However, this material is not very well characterized and contains a wide variety of compounds in gas, liquid, and solid forms. This project will develop a comprehensive mathematical model for the torrefaction of biomass that will predict the energy requirements and final product mixture, using knowledge of the detailed reaction processes. This model will then be used to develop torrefaction processes that can be tailored to make an energy-dense, low-oxygen material from woody biomass. Research results will be used to provide examples in engineering classes at undergraduate and graduate levels, and to enable the development of classroom materials on biofuel topics for high school students through the involvement of high school teachers in research.The goal of this research is to develop a comprehensive model for the elementary reactions and kinetics during the torrefaction of the hemicellulose fraction of woody biomass. In torrefaction, the biomass is heated in an inert atmosphere at 200 to 300 degrees C. It is hypothesized that pericyclic reactions, which are known to describe cellulose pyrolysis accurately, also describe the torrefaction of hemicellulose. The model will be developed using reaction kinetics experiments, computational quantum chemistry, and reaction theory. Thermogravimetric analyses will provide instantaneous heats of pyrolysis. Product gases and vapors will be profiled in real time by two-dimensional gas chromatography with time-of-flight mass spectrometry (GCxGC-TOFMS). These experiments will be carried out with solid samples of woody biomass (loblolly pine), the hemicellulose biopolymers xylan and galactoglucomannan, and hemicellulose monomers xylose, arabinose, mannose, and galactose. The reaction processes for the flash pyrolysis of the torrefied solids will be studied by online GCxGC-TOFMS analysis of the bio-oil product vapors, complimented by analysis of the residual solid structures using solid-state nuclear magnetic resonance (NMR). Quantum-chemistry analyses of monomer torrefaction will be expected to yield additional mechanistic insights. The full model will predict reaction kinetics and products of the torrefaction of cellulose and hemicellulose fractions of woody biomass. Educational activities based on the research include mentoring of an undergraduate process design team on the design of a thermochemical biomass processing plant, development of course materials for reaction kinetics and transport courses at the undergraduate and graduate levels, and research experiences for undergraduates and high school teachers.