Surface Studies of Multifunctional Oxygenates on Metals

CBET-0828767 MedlinIntellectual merit。从生物质衍生糖生产燃料和化学品的综合生物精炼厂的发展对催化提出了许多关键挑战。在这些挑战中，需要设计对多功能氧分子中单个官能团的反应具有选择性的催化剂。几乎所有所谓的生物精炼基本分子？包括多元醇，乙酰丙酸及其衍生物？包含至少两个通常含氧的官能团。在多元醇的情况下，这些官能团是不变的，而在其他情况下（如左丙酸及其环衍生物），各种官能团是不同的。然而，在所有情况下，希望能够控制对单一功能位置的反应性。为了设计具有可控选择性的催化剂结构，需要更好地了解多功能氧合物在关键催化表面（如pt基金属）上采用的结合构型。提出了多种多功能氧合物在Pd（111）表面的吸附和热化学研究，重点是多元醇和环酯或醚。高分辨率电子能量损失光谱将用于表征吸附质结构和识别反应中间体，温度程序解吸将用于跟踪吸附质解吸动力学和挥发性反应产物的演变。密度泛函理论计算将被用作促进光谱结果的原子尺度解释的工具。在这些含氧化合物的吸附和热化学研究中，分子参数如官能团的数目、官能团之间的间距和烷基链的长度会发生变化。提出的工作的主要目的是确定氧分子中多个官能团的存在如何影响吸附和表面反应途径。这一系列研究的最终目标是帮助制定策略，以更好地控制复杂碳水化合物分子中单个官能团的反应性。虽然这一目标需要考虑表面结构和组成的变化如何改变表面过程，但本提案的主要重点是彻底评估分子本身的变化如何控制表面化学。更广泛的影响。在表面上具有多个官能团的分子的反应中实现选择性控制的总体目标，将对与石油和生物质衍生化学品生产有关的许多应用产生革命性的影响。此外，多元醇和呋喃等化合物的表面化学在生物精炼概念和传统化学领域都很重要。因此，更好地了解控制吸附物多重结合的因素可能对许多工业产生影响。拟议的研究与科罗拉多生物精炼和生物燃料中心（C2B2）的目标非常一致，该中心是一个由工业界支持的中心，PI是科罗拉多大学的现场主任。该项目将受益于与C2B2相关的几个项目，包括一个模仿NSF REU项目的项目，一个博士后项目，以及与行业赞助商的定期会议。本文还提出了少数民族本科生研究人员参与本研究的方案。

CBET-0828767 MedlinIntellectual merit. The development of integrated biorefineries for production of fuels and chemicals from biomass-derived sugars poses a number of key challenges for catalysis. Among these challenges is the need to design catalysts that are selective for reactions of a single functional group within a multifunctional oxygenate molecule. Nearly all of the so-called biorefining building block molecules?including polyols, levulinic acid, and their derivatives?incorporate at least two functional groups that are typically oxygen-containing. In the case of polyols these functional groups are invariant, whereas in other cases (such as for levulinic acid and its cyclic derivatives) the various functional groups are distinct. In all cases, however, it is desirable to be able to control reactivity to a single functional position. To design catalyst structures with controlled selectivity, a better understanding is needed of the binding configurations adopted by multifunctional oxygenates on key catalytic surfaces, such as Pt-group metals. It is proposed to study the adsorption and thermal chemistry of a variety of multifunctional oxygenates, focusing on polyols and cyclic esters or ethers, on the Pd(111) surface. High resolution electron energy loss spectroscopy will be employed to characterize adsorbate structure and to identify reaction intermediates, and temperature programmed desorption will be used to track the kinetics for adsorbate desorption and the evolution of volatile reaction products. Density functional theory calculations will be employed as a tool to facilitate atomic-scale interpretation of spectroscopic results. Molecular parameters such as the number of functional groups, the spacing between functional groups, and the length of pendant alkyl groups will be varied in the studies of adsorption and thermal chemistry of these oxygenates. The primary objective of the proposed work is to identify how the presence of multiple functional groups in oxygenate molecules affects adsorption and surface reaction pathways. The ultimate goal of this line of research is to aid in developing strategies for achieving better control over reactivity toward a single functional group in a complex carbohydrate molecule. While this goal will require consideration of how surface processes are altered by changes in surface structure and composition, the principal focus of this proposal is on a thorough assessment of how changes in the molecules themselves control surface chemistry. Broader impact. The general objective of achieving selectivity control in reactions of molecules with multiple functional groups on surfaces would be transformative for many applications related to production of both petroleum- and biomass-derived chemicals. Furthermore, the surface chemistry of compounds such as polyols and furans is important both within the biorefining concept and in the traditional chemical sector. A better understanding of the factors controlling multiple binding of adsorbates could therefore make an impact in a number of industries. The proposed research is well-aligned with the objectives of the Colorado Center for Biorefining and Biofuels (C2B2), an industry-supported center for which the PI is the University of Colorado site director. The project will benefit from several programs associated with C2B2, including a program modeled after the NSF REU program, a postdoctoral fellows program, and regular meetings with industry sponsors. A program for involvement of minority undergraduate researchers in this research is also proposed.