Mechanism for Heterogeneously Catalyzed Sugar Alcohol Reactions: Hierarchical Modeling and Experimental Studies

摘要标题：水溶液中醇类制氢化学过程的分子水平模拟可持续性和环境影响的最新驱动因素导致了将植物衍生化学品转化为有用的能源和特种化学品产品的过程。在许多情况下，用于转化这些化合物的技术依赖于昂贵的催化剂。例如，用作无污染燃料的氢可以使用由铂、钯、铑和其它贵金属组成的催化剂由植物衍生的醇生产。这些催化剂材料的高成本渗透到醇转化成本中，限制了这些植物来源的原料的经济可行性，以及它们与常规石油来源的化学品的竞争力。理论上，可以设计更便宜的转化催化剂。寻找良好催化剂的主要挑战之一来自用于处理这些植物源性原料的水相反应环境。这些密集的水性环境显著增加了在分子水平上参与的分子数量，使得难以评估它们的精确作用。该奖项授予克莱姆森大学的Rachel Getman和大卫布鲁斯教授，他们利用分子模拟技术和实验的层次来确定水影响甲醇和甘油制氢的分子水平化学的具体方式，甲醇和甘油是生物燃料生产的副产品。这项研究也将作为本科生和研究生的优秀培训平台，让他们接触计算和实验技术，并使他们能够智能地解决未来的科学和社会问题。网络视频和演示将使更多的受众能够跟踪项目的进展情况，了解主要的研究成果。未来的工作将旨在设计用于甲醇和甘油转化以及其他溶液相转化的较便宜的催化剂。许多催化反应发生在液相中，了解液体中的分子水平现象是催化研究的前沿。很少有基础反应研究探索了水溶剂环境如何影响多相催化中涉及的熵和熵驱动力。为了获得优化水相反应系统所需的洞察力，该项目的目标是阐明两个重要的水相反应的分子水平机制，特别是甲醇氧化和甘油重整，这是目前在含有铂和其他贵金属的非均相催化剂上进行的（类似于生物质加工中涉及的许多其他反应）。该项目采用了分子水平的建模和实验的层次结构，以确定甲醇氧化和甘油重整机制中最突出的步骤。量子力学，统计力学，蒙特卡罗和分子动力学将被用来模拟水环境如何影响催化现象。最终，量子数据和详细的微观动力学模型将确定整体产品的选择性，模拟结果将与实验观察进行比较，用于验证和模型改进。这项研究是潜在的变革，因为它将阐明吸附剂-中间体相互作用，吸附剂-流体相互作用，以及它们的耦合，从而提供了一个完整的分析，在液相中的催化机制，并促进未来的工作在催化剂设计的一个重要类别的液相反应。

Abstract Title: Molecular-level simulations of the chemistry of hydrogen generation from alcohols in aqueous solutions Recent drivers of sustainability and environmental impact have led to processes for converting plant-derived chemicals into useful products for energy and specialty chemicals. In many cases, the technologies used to convert these compounds rely on expensive catalysts. For example, hydrogen for use as a pollutant-free fuel can be produced from plant-derived alcohols using catalysts comprised of platinum, palladium, rhodium, and other noble metals. The high costs of these catalyst materials percolate into the alcohol conversion costs, limiting the economic viability of these plant-derived raw materials, as well as their competitiveness with conventional petroleum-derived chemicals. Theoretically, less expensive conversion catalysts could be designed. One of the major challenges to finding good catalysts arises from the aqueous phase reaction environment used to process these plant-derived raw materials. These dense, aqueous environments significantly increase the number of molecules that are involved at the molecular level, making it difficult to evaluate their precise roles. This award is to Professors Rachel Getman and David Bruce of Clemson University to utilize a hierarchy of molecular simulation techniques as well as experiments to identify specific ways that water influences molecular-level chemistry for hydrogen production from methanol and glycerol, which are available byproducts of biofuel production. This study will also serve as an excellent training platform for undergraduate and graduate students, exposing them to computational and experimental techniques, and empowering them to intelligently address future scientific and societal problems. Web-based videos and presentations will enable a wider audience to follow the progress of the project and learn about key research findings. Future work will be aimed at designing less expensive catalysts for methanol and glycerol conversions as well as other solution-phase transformations. Many catalyzed reactions occur in the liquid phase, and understanding molecular-level phenomena in liquids is at the forefront of catalysis research. Few fundamental reaction studies have explored how an aqueous solvent environment impacts the entropic and enthalpic driving forces involved in heterogeneous catalysis. To acquire the insight needed to optimize aqueous reaction systems, the objectives of this project are to elucidate the molecular-level mechanisms of two important aqueous phase reactions, specifically methanol oxidation and glycerol reforming, which are currently carried out over heterogeneous catalysts containing platinum and other noble metals (similar to many other reactions involved in biomass processing). This project employs a hierarchy of molecular-level modeling and experiments to identify the most prominent steps in the methanol oxidation and glycerol reforming mechanisms. Quantum mechanics, statistical mechanics, Monte Carlo, and molecular dynamics will be used to model how the aqueous environment influences catalytic phenomena. Ultimately, quantum data and detailed microkinetic models will identify overall product selectivities, and simulation results will be compared with experimental observations for both validation and model improvement purposes. This research is potentially transformative in that it will elucidate adsorbate-intermediate interactions, adsorbate-fluid interactions, and their coupling, thus, providing a complete analysis of catalytic mechanisms in the liquid phase, and facilitating future work in catalyst design for a vital class of liquid phase reactions.