Multiscale Modeling of Bifunctional Catalysts for the Water-Gas-Shift Reaction

水煤气变换反应双功能催化剂的多尺度建模

• 批准号: 0932991
• 负责人: Andreas Heyden
• 金额: $ 30万
• 依托单位: University South Carolina Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-15 至 2012-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0932991&HistoricalAwards=false
• 关键词: Multiscale; Modeling; Bifunctional; Catalysts; Water

0932991 HeydenThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Intellectual Merit - For heterogeneously catalyzed reactions with more than one key surface intermediate, it is likely that multiphase catalysts have a significant advantage over conventional monophase catalysts since each phase can potentially be adjusted independently to activate a key reaction step. At the same time, understanding of bifunctional multiphase systems is relatively poor. It is the objective of this proposed research program to significantly enhance molecular understanding of heterogeneous catalysis at the three-phase boundary (TPB) of a gas-phase, a reducible oxide surface, and a noble metal cluster. To enable this theoretical investigation of chemical reactions at the TPB, the PI and his students propose to develop and validate a highly efficient and accurate computational strategy for these systems. It is their firm belief that only with a more accurate computational multiscale strategy that permits the reliable investigation of reactions on strongly correlated reducible oxide surfaces and metal clusters, will it be possible to truly understand the nature of the active sites, the origin of catalytic activity, and the reaction mechanism at the TPB under reaction conditions. As a model system for computational study, they intend to investigate the water-gas-shift (WGS) reaction on titania and ceria supported mono- and bimetallic clusters of Au, Pt, and Pd. Their computational strategy and study of the nature of the active site at the TPB is not limited to the WGS reaction but is likely more general as it has been shown that reducible oxide supported noble metals are highly active for various reactions such as the selective hydrogenation and oxidation of unsaturated hydrocarbons. Their computational strategy involves state-of-the-art periodic slab calculations to build and validate a periodic electrostatic embedded cluster model that is used for the study of various reaction pathways. Unlike periodic slab models, the periodic cluster model permits the use of modern doublehybrid density functionals with significantly improved accuracy for modeling chemical reactions on reducible oxide surfaces and metal clusters. Having determined reasonably accurate reaction energies and barriers, they intend to develop a microkinetic reactor model based on data obtained only from first principles and absolute rate theory. With the help of the microkinetic model, they will be able to study the effect of temperature and chemical potential of the gas phase on the reaction mechanism and key reaction intermediates. Furthermore, they will be able to determine the origin of the activity of the active sites by analyzing how the electronic structure is altered with changes in noble metal cluster and reducible oxide and by using Nørskov's method to distinguish electronic effects from geometric or structural effects. Finally, it is noted that the computational models and methods outlined in this proposal have not been used previously in the study of heterogeneous catalysis and collaboration with experimentalists such as Dr. Amiridis and Dr. Chen at USC is proposed to validate and test the computational predictions.Broader Impact, Science - The development of a more accurate computational strategy for studying reactions at the TPB of a gas-phase, a reducible oxide surface, and a noble metal cluster will significantly increase the reliability of theoretical investigations of these surprisingly catalytically active systems that are computationally very difficult to describe. Furthermore, understanding of the origin of the unique catalytic activity of these systems will likely aid the development of improved catalysts for various reactions that can be selectively activated by oxide supported noble metals.Broader Impact, Education - The graduate and undergraduate students directly involved in the proposed research will be exposed to a comprehensive set of theoretical tools that will allow them to study most issues in catalysis and material science. In addition, the results of the proposed research will be integrated in a joint graduate and undergraduate course "Multiscale Modeling: From Electrons to Chemical Reactors" that is currently being developed by the PI. Community Outreach - The graduate student involved in this research will spend one Fall semester in the Partners in Inquiry program at USC. She will assist a science teacher from a local middle school (82% African American or Hispanic origin) to integrate engineering and science content (including her research) and problem solving methods into the science curriculum. Finally, the PI is involved in the Enhanced Learning Experience (ELE) program at USC, in which high school students interested in chemical engineering are given a one day hands-on learning experience.

0932991 Heyden该奖项根据 2009 年美国复苏和再投资法案（公法 111-5）提供资助。 智力成果 - 对于具有多个关键表面中间体的非均相催化反应，多相催化剂可能比传统单相催化剂具有显着优势催化剂，因为每个相都可以独立调节以激活关键反应步骤。同时，对双功能多相系统的了解相对较少。该研究计划的目标是显着增强对气相、可还原氧化物表面和贵金属簇的三相边界（TPB）多相催化的分子理解，从而实现化学反应的理论研究。在 TPB，PI 和他的学生提议为这些系统开发和验证高效且准确的计算策略，他们坚信，只有更准确的计算多尺度策略才能对相关可还原氧化物的反应进行可靠的研究。表面和金属簇，是否有可能真正了解活性位点的性质、催化活性的起源以及反应条件下TPB的反应机制，作为计算研究的模型系统，他们打算研究水-气-反应。他们的计算策略和对 TPB 活性位点性质的研究不仅限于 WGS 反应，而且可能更通用。作为研究表明，可还原氧化物负载的贵金属对各种反应具有高度活性，例如不饱和烃的选择性加氢和氧化，其计算策略涉及最先进的周期性平板计算，以构建和验证周期性静电嵌入簇。用于研究各种反应路径的模型，与周期性板模型不同，周期性簇模型允许使用现代双混合密度泛函，并且显着提高了对可还原氧化物表面和金属上的化学反应进行建模的准确性。在确定了相当准确的反应能量和势垒后，他们打算根据仅从第一原理和绝对速率理论获得的数据开发微动力学反应器模型，在微动力学模型的帮助下，他们将能够研究温度的影响。此外，他们将能够通过分析电子结构如何随贵金属簇和可还原氧化物的变化来确定活性位点的活性来源。通过使用 Nørskov 方法最后，值得注意的是，该提案中概述的计算模型和方法之前尚未用于多相催化的研究以及与 Amiridis 博士和 Chen 博士等实验者的合作。 USC 旨在验证和测试计算预测。更广泛的影响，科学 - 开发更准确的计算策略来研究气相、可还原氧化物表面和贵金属簇的 TPB 反应将显着提高理论的可靠性此外，对这些令人惊讶的催化活性系统的研究在计算上很难描述，了解这些系统独特催化活性的起源可能有助于开发可被氧化物负载的贵金属选择性激活的各种反应的改进催化剂。 .更广泛的影响，教育-直接参与拟议研究的研究生和本科生将接触到一套全面的理论工具，使他们能够研究催化和材料科学中的大多数问题。此外，拟议研究的结果。将纳入研究生和本科生联合课程“多尺度建模：从电子到化学反应器”，该课程目前由 PI 社区外展开发 - 参与这项研究的研究生将在南加州大学的合作伙伴探究项目中度过一个秋季学期。她将协助当地中学的科学老师（82％为非裔美国人或西班牙裔）将工程和科学内容（包括她的研究）和解决问题的方法融入到科学课程中。学习经历南加州大学的 (ELE) 项目，为对化学工程感兴趣的高中生提供一日实践学习体验。