Designing and characterizing highly selective heterogeneous catalysts for hydrodeoxygenating bio-oils

大多数废流，包括工业木材副产品和城市固体废物，一般都是环境和经济负担；但它们有可能成为制造燃料、药品和其他消费品的原料。然而，要将这些废物转化为有用的东西，需要进行一些化学反应。最具挑战性的化学变化之一是从废物中去除多余氧原子的反应。我们的团队设计了催化剂，即通过提高速度、选择性和/或能源需求来帮助反应的材料，但本身不会在反应中消耗。我们正在积极开发、表征和测试催化剂，利用氢气从这些废气中脱除油中的多余氧气。我们的团队结合了制造催化剂和在分子水平上控制其结构、确定所产生的反应产品的类型、优化反应器流程以提高效率以及通过理论建模来了解固体催化剂及其控制的反应的专业知识。我们能够一起设计和研究各种催化剂，以测试有关该反应的最佳催化剂如何工作的具体想法，并引导我们设计出使用地球上丰富的金属的更好、更环保的催化剂。这项研究的更广泛影响包括消除废物的环境效益和从废物中生产化学燃料和原料来源的经济效益。我们团队的所有成员都致力于使科学队伍多样化，并参与在我们的实验室中招募和留住在科学领域历来代表性不足的群体成员的活动。我们积极参与课程改革，并从当前提高能源生产可持续性的科学努力中提取案例，构成了纽约巴纳德学院新设计的普通化学课程的基础。在这个研究计划中，奥斯汀、弗雷德里克、格拉博和施瓦茨博士得到了美国国家科学基金会的高分子、超分子和纳米化学计划的支持，以测试以下假设：适合于裂解C-O键的高选择性加氢脱氧(HDO)反应的催化材料需要：(1)能够吸附和分解H2的金属；和(2)两性载体，它可以充当质子从金属到衬底的穿梭，以削弱C-O键。如果得到证实，这项工作的结果可能会改变当前的范式，引用支持简约性，而不是它的两性特征。人们正在合成一系列负载型金属催化剂，并用各种实验和计算方法对其进行表征。这些催化剂用于催化苯酚衍生的模型化合物与氢气的HDO反应，包括一些同位素标记的底物。用气相色谱-质谱仪(GC-MS)对HDO反应产物进行了分析。用密度泛函理论(DFT)计算了反应能量分布，并与实验数据进行了比较，提出了详细的催化反应机理。这项研究的更广泛影响包括消除废物的环境效益和从废物中生产化学燃料和原料来源的经济效益。在四个非常不同的实验室之间交换学生：休斯顿大学的计算实验室，缅因州大学的化学工程实验室和物理化学实验室，以及纽约市一所女子文科学院的无机催化实验室，将促进参与该项目的学生的广泛发展。利用这项工作和其他可持续能源发展研究的案例，重要的课程开发构成了以问题为基础的普通化学课程的基础，该课程每年为大约150名巴纳德学院的女学生服务。

The majority of waste streams, including industrial timber by products and municipal solid waste, are generally environmentally and economically burdensome; yet they have the potential to serve as starting materials from which fuels, medicines and other consumer products can be made. However, a number of chemical reactions are required to transform these waste materials into something useful. Among the most challenging chemical changes needed are reactions that remove excess oxygen atoms from the waste material. Our team designs catalysts, materials that aid in a reaction by improving speed, selectivity and/or energy requirements, but do not themselves become consumed in the reaction. We are actively developing, characterizing and testing catalysts that use hydrogen gas to remove excess oxygen from oils made from these waste streams. Our team combines expertise in making catalysts and controlling their structure at the molecular level, identifying the type of reaction products that result, optimizing the reactor process for greater efficiency, and theoretical modeling to understanding the behavior of solid catalysts and the reactions they control. Together, we are able to design and study a wide range of catalysts selected to test specific ideas about how optimal catalysts for this reaction work and also to lead us towards the design of better and more environmentally friendly catalysts that use earth-abundant metals. Broader impacts of the research include environmental benefits of eliminating waste and economic benefits of producing a chemical fuel and feedstock source from waste products. All members of our team are committed to diversifying the scientific workforce and are engaged in activities to recruit and retain in our laboratories members of groups historically underrepresented in scientific fields. We engage in active curriculum reform, and cases drawn from current scientific efforts to improve the sustainability of energy production form the foundation of the newly redesigned General Chemistry course at Barnard College, an all-women's college in New York City.In this research program, Drs. Austin, Frederick, Grabow, and Schwartz are supported by the Macromolecular, Supramolecular and Nanochemistry Program at NSF to test the hypothesis that catalytic materials suitable for highly selective hydrodeoxygenation (HDO) reactions that cleave C-O bonds require: (1) a metal that can adsorb and split H2; and (2) an amphoteric support that can serve as a proton shuttle from the metal to the substrate to weaken the C-O bond. If confirmed, the results from this work could alter the current paradigm invoking support reducibility rather than its amphoteric character. A series of supported metal catalysts is being synthesized and characterized using a variety of experimental and computational methods. These catalysts are used to catalyze HDO reactions of phenol-derived model compounds, including some isotopically-labeled substrates, with hydrogen gas. The products of the HDO reactions are analyzed by gas chromatography-mass spectrometry (GC-MS) measurments. Density functional theory (DFT) is used to calculate reaction energy profiles, which are then compared to experimental data to propose detailed catalytic reaction mechanisms. Broader impacts of the research include environmental benefits of eliminating waste and economic benefits of producing a chemical fuel and feedstock source from waste products. Student exchange between four very different labs: a computational lab at the University of Houston, a chemical engineering lab and a physical chemistry lab both at the University of Maine, and an inorganic catalysis lab at an all women's liberal arts college in New York City, will facilitate the broad development of students working on this project. Significant curriculum development, using cases from this work and from other research on sustainable energy development, forms the basis of a problem-based general chemistry course that serves approximately 150 female Barnard College students each year.