CAREER: Fundamental Chemistry of Combustion Intermediates: Cyclic Ethers

美国能源信息机构预测，未来几十年，运输业消耗的燃烧衍生能源的比例仍与2020年惊人地相似，碳氢化合物和生物燃料将提供约97%的能源。在其他技术的同时，继续开发用于交通的可持续燃烧系统是美国的优先事项。尽管多年来取得了许多进展，包括排放量的大幅减少和燃料经济性的改善，但在开发可持续和低碳密集型能源方面，仍然存在重大的科学挑战。燃烧系统效率的提高取决于对控制点火和污染物形成的化学反应的了解，以及通过计算机建模预测此类现象的能力。然而，在下一代燃烧系统中，对碳氢化合物和生物燃料化学的基本理解变得更加复杂，因为新一代燃烧系统采用了不同于传统系统的新策略和温度和压力操作条件。该项目特别关注环醚，这是现代燃烧系统中主要在低温下形成的一类中间体。为了促进下一代燃烧技术的能源效率目标，这个职业项目将研究、教育和推广战略紧密结合起来，以产生基础知识和教学工具，促进燃烧化学领域的发展。该项目包括对博士生、本科生、退伍军人和第一代学生的科学培训。这些研究内容是几个教育项目的基础，其中包括与新闻学院合作制作的燃烧科学视频，研究生和本科生在视频中讨论他们的研究及其更广泛的影响，以激发人们对燃烧研究的兴趣。该项目的主要研究活动包括使用高压喷射搅拌反应器对环醚进行燃烧实验，以及使用领先的化学动力学建模开源软件Reaction Machine Generator开发新的子机理。该项目特别关注环醚自由基化学，单分子开环和双分子与氧反应之间竞争的知识差距，以及对点火和排放预测的相关影响。这些实验利用质谱仪和最先进的电子吸收光谱技术来测量正戊烷氧化产生的六种环醚燃烧产物的异构体解析物种分布：1，2-环戊烷、2，3-环戊烷、2-乙氧基硅烷、2，4-二甲氧基硅烷、2-甲基四氢呋喃和四氢吡喃。这项研究的科学影响包括对与燃烧相关的化学反应性的新的、基本的理解，新的环醚子机制，以及对现有化学动力学机制的保真度的改进，这使得下一代燃烧系统的设计和建模成为可能。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The U.S. Energy Information Agency predicts that portion of combustion-derived energy consumed by the transportation sector over the next several decades remains strikingly similar to that in 2020, with hydrocarbons and biofuels providing about ninety-seven per cent. Concurrent with other technologies, continued development of sustainable combustion systems for transportation is a high priority for the United States. Despite numerous advancements over the years, including drastic reductions in emissions and improvements in fuel economy, significant scientific challenges still remain on development of sustainable and low-carbon-intensive energy sources. Improvements in the efficiency of combustion systems is predicated on an understanding of chemical reactions that control ignition and pollutant formation and, moreover, the ability to predict such phenomena via computer modeling. However, fundamental understanding of hydrocarbon and biofuel chemistry becomes more complex in next-generation combustion systems that incorporate new strategies and operating conditions of temperature and pressure that differ from conventional systems. This project specifically focuses on cyclic ethers, which are a class of intermediates formed predominantly at low temperatures as found in modern combustion systems. To contribute to energy efficiency goals for next-generation combustion technologies, this CAREER project tightly integrates research, education, and outreach strategies to produce fundamental knowledge and instructional tools to advance the field of combustion chemistry. This project includes scientific training of Ph.D. students, undergraduate Student Veterans, and first-generation students. The research elements underpin several educational projects, including, among others, combustion science videos produced in collaboration with the Grady School of Journalism, wherein graduate and undergraduate students discuss their research and its broader impact to spur interest in combustion research. The primary research activities of the project involve combustion experiments on cyclic ethers using a high-pressure jet-stirred reactor and the development of new sub-mechanisms using Reaction Mechanism Generator, a leading open-source software for chemical kinetics modeling. The project specifically focuses on cyclic ether radical chemistry, the knowledge gap on the competition of between unimolecular ring-opening and bimolecular reaction with oxygen, and related impact on ignition and emissions predictions. The experiments utilize mass spectrometry and a state-of-the-art electronic absorption spectroscopy technique to measure isomer-resolved species profiles of products from combustion of the six cyclic ethers produced from n-pentane oxidation: 1,2-epoxypentane, 2,3-epoxypentane, 2-ethyloxetane, 2,4-dimethyloxetane, 2-methyltetrahydrofuran, and tetrahydropyran. The scientific impact of this research includes the development of new, fundamental understanding of chemical reactivity relevant to combustion, new cyclic ether sub-mechanisms, as well as improvements to the fidelity of existing chemical kinetics mechanisms, which enable the design and modeling of next-generation combustion systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.