CAREER: Inorganic-organic hybrid microreactors for fundamental study of cellulose hydrolysis by solid acids

摘要：木质纤维素生物质是世界上最丰富的可再生碳来源，有望成为碳中和能源，可以减少对石油基运输燃料、化学品和材料的需求。尽管许多不同的生物燃料技术在发展方面取得了进展和前景，但没有一种技术在经济上是可行的。该项目的目的是使从生物质资源生产燃料和化学品在经济上可行。生物质转化为燃料和化学品的经济效益不佳，主要是由于生物质对化学和生物攻击的抵抗力。已经提出了克服生物质顽固性的三个主要平台：生物油（通过热解或液化产生），合成气（通过气化产生）和糖（通过预处理和酶水解产生）。这个提议主要是针对糖的平台。生物质对化学和生物侵害的抗性使得单糖的回收成本高且耗能大。这项工作的重点是从生物质中回收单糖，因为这一步代表了糖平台的关键技术瓶颈。总体的研究目标是了解纤维素的基本机制解构固体酸催化剂。该方法包括构建聚合物刷改性无机颗粒（二氧化硅和沸石）作为催化微反应器，具有：1)明确的外部酸度，可被不溶性底物访问；2)纤维素靶向/结合/增溶能力，可提供不溶性底物与固体酸的外表面之间的相互作用；3)内部孔隙结构和酸度，可被小分子可溶性底物访问。需要解决的具体问题包括：1)控制催化剂-生物质相互作用的结构/性质-功能关系是什么？2)固体酸强度与纤维素水解活性的关系是什么？3)纤维素链断裂的外部酸度和可溶性片段水解的内部酸度之间的平衡是什么？该项目将评估固体酸催化是由结合相互作用和强酸性介导的假设。在本工作的研究部分，将研究其潜在的机制：1)了解催化剂与纤维素结合的作用以及纤维素粘附、催化剂表面组成和催化剂表面能之间的关系；2)量化酸度的作用，并回答催化水解所需表面酸度的问题；3)区分转化不溶性底物所需的外部酸性位点和能够转化可溶性碳水化合物的内部酸性位点。研究目标将与教育和推广目标相结合，利用数据到音乐的工具，吸引来自代表性不足背景的学生从事STEM领域的职业，并在本科阶段吸引比工程课程更广泛的学习方式。在教育方面，利用音乐向工科大学生教授困难的概念，可以改善对那些使用工程课程中不典型的学习方式的学生的训练。这有可能提高STEM领域更广泛的本科生的保留率。外展部分将为K-12学生提供引人入胜的STEM体验，赋予他们力量，而不是疏远他们。具体来说，研究数据将被转换成声音并重新调制成音乐，这一过程模仿了驱动嘻哈音乐创作的采样实践。

Abstract - Timko, 1554283Lignocellulosic biomass, the world's most abundant source of renewable carbon, has promise as a carbon neutral energy source that can reduce the need for petroleum-based transportation fuels, chemicals, and materials. Despite progress and promise in the development of many different biofuel technologies, none have proven economically viable. The aim of this project is to make production of fuels and chemicals from biomass resources economically viable. The poor economics of biomass conversion to fuels and chemicals is due largely to biomass resistance to chemical and biological attack. Three primary platforms have been suggested for overcoming biomass recalcitrance: bio-oil (produced via pyrolysis or liquefaction), synthesis gas (produced by gasification), and sugars (produced by pretreatment and enzyme hydrolysis). This proposal is focused on the sugars platform. Biomass resistance to chemical and biological attack makes recovery of monosaccharides expensive and energy intensive. The focus of this work is on recovery of monosaccharides from biomass because this step represents the key technological bottleneck of the sugars platform.The overarching research objective is to understand the fundamental mechanisms underlying cellulose deconstruction by solid acid catalysts. The approach consists of constructing polymer-brush modified inorganic particles (silica and zeolites) as catalytic microreactors with: 1) well defined external acidity that can be accessed by insoluble substrates, 2) cellulose targeting/binding/solubilization capability to provide interactions between insoluble substrates and external surfaces of solid acids, and 3) internal pore structure and acidity that can be accessed by small molecule soluble substrates. Specific questions to be addressed include: 1) what is the structure/property- function relationship that governs the catalyst-biomass interaction? 2) what is the relationship between solid acid strength and cellulose hydrolysis activity? and 3) what is the balance between external acidity for cellulose chain breaking and internal acidity for hydrolysis of soluble fragments? The project will evaluate the hypothesis that solid acid catalysis is mediated by binding interactions and strong acidity. In the research component of this work, the underlying mechanism will be examined to: 1) understand the role of catalyst-cellulose binding and the relationship between cellulose adhesion, catalyst surface composition, and catalyst surface energy; 2) quantify the role of acidity and answer the question of how acidic the surface needs to be to catalyze hydrolysis; 3) differentiate between external acidic sites required to convert insoluble substrates and internal acidic sites capable of converting soluble carbohydrates.The research objectives will be integrated with educational and outreach aims to use data-to-music tools to attract students from under-represented backgrounds to careers in STEM fields and to appeal to a broader range of learning styles at the undergraduate level than are typical in the engineering curriculum. In terms of education, the use of music to teach difficult concepts to college engineering students could improve training for students that use learning styles that are not typical in engineering curricula. This has potential to improve retention of a broader range of undergraduate students in STEM fields. The outreach component will provide K-12 students with an engaging STEM experience that empowers rather than alienates. Specifically, research data will be converted into sounds and re-modulated into music, a process that mimics the practice of sampling that drives hip hop music composition.