A rational approach to the evaluation of supported metals and surface alloys as oxidation and reforming catalysts

评估负载金属和表面合金作为氧化和重整催化剂的合理方法

• 批准号: 0828666
• 负责人: Maria Flytzani-Stephanopoulos
• 金额: $ 39.26万
• 依托单位: Tufts University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-10-01 至 2011-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0828666&HistoricalAwards=false
• 关键词: rational; approach; evaluation; supported; metals

Intellectual Merit This project builds on exciting new findings from current work at Tufts University under an NSF/NIRT grant, in which we have collected significant evidence pointing to atomic dispersions of gold and platinum in ceria, and gold in iron oxide, as the catalytic sites for the water gas shift reaction (WGS). We followed activity loss with gold cluster growth in ceria matrices and identified conditions that stabilize gold growth. We have shown that addition of small amounts of oxygen can be used to stabilize Au- or Pt-CeO2 shift catalysts at all temperatures and in cyclic start up/ shutdown operation in realistic fuel gas streams. We have further demonstrated a strong shape/crystal face/strain effect of ceria on the WGS activity of Au/ceria by using single ceria crystals at the nanoscale prepared by controlled hydrothermal synthesis, which can be tested at normal pressures in flow reactor systems. Moreover, this project builds on new, important theoretical findings from the University of Wisconsin that certain pairs of metals examined as surface or near surface alloys possess much improved activity as PEM cathode electrocatalysts. The unique capability in high-resolution STM/STS of one of the Tufts co-PIs will open a new avenue of investigation that connects atomic-level composition and electronic properties with the surface chemistry of these model catalysts. In the proposed work, we will extend the study of atomic dispersions of metals to other oxides, such as zirconia and zinc oxide, both prepared by novel synthesis routes as nano rods, cubes, polyhedra, etc. exposing specific crystal planes on which to deposit and study metals and metal alloys. The WGS and methanol steam reforming (MSR) processes will be the reactions of interest to probe structure sensitivity with the support. Metals and near surface metal alloys from the group of Au, Cu, Pd, and Pt, will be examined. A new combinatorial approach to rank order alloy metal reactivity is proposed, whereby nanoalloy tips pressed on thin oxides-on-thermocouple junctions will be constructed in arrays and thermoelectric response will be used to monitor adsorption/reaction on the nanoalloys. A rational approach to the synthesis and evaluation of novel catalysts for WGS and MSR is proposed to complement and guide the catalysis work. Thus, STM/STS studies and computational chemistry are center-stage in the project. We will also make use of the XAS capabilities at Brookhaven National Lab (BNL) through our collaborators there. Our overall goal in the project is to elucidate the metal-oxide and the metal-metal interactions responsible for redox reactions of interest to fuel reforming for hydrogen generation and pave the way for the design of the next generation of WGS and MSR catalysts. Broader Impacts We propose to undertake a systematic, multidisciplinary research effort to investigate the atomic-level interaction of Au, Cu, Pt, and Pd with ceria, zirconia, or zinc oxide for two reactions of interest to the production of hydrogen for fuel cells; namely, the water-gas shift and methanol steam reforming reactions. Knowledge garnered from these systems has both mechanistic and practical implications for other closely related reactions of importance to clean energy, including the processing of other oxygenates derived from fossil fuels or biomass. An interdisciplinary team of experts from Chemical Engineering and Chemistry at Tufts, Chemical Engineering at the Wisconsin, and Chemistry at BNL, has been assembled for this project. At the end of the interdisciplinary effort, we will have answered key questions on the activity and selectivity of atomically dispersed metals, metal clusters, and supported surface alloys on nanoparticles of ceria, zirconia, or zinc oxide, and be in a position to provide rational designs for practical catalyst preparation. These materials will be used in fuel and biofuel processing, and as anode catalysts and films for fuel cell applications. Thus, the impact of these findings will lead to better power systems design. There are several other tangible benefits for each of the disciplines involved here: new methods for catalyst synthesis, new materials properties specific to the nanoscale of importance to sensors, fuel cell components, and to catalysts; and new catalyst designs for low-cost fuels and chemicals production. An overall benefit will be a template for the rational design of catalysts derived from the interdisciplinary activities of the project. In what has become a tradition in our laboratories, we regularly exchange information with industrial colleagues. In this project, we plan to involve industrial colleagues as technical advisors, both for science and possibly for technology transfer. The interdisciplinary nature of the proposal clearly impacts the education of graduate students and postgraduate fellows. Extensive training of young researchers at BNL is also planned in the project. A significant number of women students will be involved in the project, and the Tufts Summer Scholars program for undergraduates will be used to recruit other under represented groups. The dissemination of the work will follow the normal channels of publications, presentations and meetings. To achieve really broad dissemination, a website will be created as part of the nano catalysis and energy site to promote this work both as an educational resource and a recruiting tool.

该项目基于塔夫茨大学在NSF/NIRT资助下目前工作的令人兴奋的新发现，其中我们收集了指向金和铂在二氧化铈中的原子分散以及金在氧化铁中的原子分散的重要证据，作为水煤气变换反应（WGS）的催化位点。我们遵循活性损失与金簇生长在氧化铈矩阵和确定的条件下，稳定金的增长。我们已经表明，添加少量的氧气可以用来稳定Au-或Pt-CeO 2变换催化剂在所有温度下，并在循环启动/关闭操作在现实的燃料气流。我们通过使用通过受控水热合成制备的纳米级的单氧化铈晶体，进一步证明了氧化铈对Au/氧化铈的WGS活性的强的形状/晶面/应变效应，其可以在流动反应器系统中在常压下进行测试。此外，该项目建立在来自威斯康星州大学的新的重要理论发现的基础上，该发现表明，作为表面或近表面合金检查的某些金属对作为PEM阴极电催化剂具有更高的活性。塔夫茨co-PI之一在高分辨率STM/STS方面的独特能力将开辟一条新的研究途径，将原子级组成和电子性质与这些模型催化剂的表面化学联系起来。在拟议的工作中，我们将扩展金属原子分散的研究，以其他氧化物，如氧化锆和氧化锌，都通过新的合成路线制备的纳米棒，立方体，多面体等，暴露特定的晶面上的存款和研究金属和金属合金。WGS和甲醇蒸汽重整（MSR）过程将是感兴趣的反应，探针结构灵敏度与支持。将检查来自Au、Cu、Pd和Pt组的金属和近表面金属合金。提出了一种新的组合方法，排名顺序合金金属反应性，从而nanoalloy尖端上薄的氧化物热电偶结将被构造在阵列和热电响应将被用来监测吸附/反应的nanoalloys。提出了一种合理的方法来合成和评价新型催化剂的WGS和MSR补充和指导的催化工作。因此，STM/STS研究和计算化学是该项目的中心阶段。我们还将通过我们在布鲁克海文国家实验室（BNL）的合作者利用XAS的能力。我们在该项目中的总体目标是阐明金属-氧化物和金属-金属相互作用，负责燃料重整制氢的氧化还原反应，并为下一代WGS和MSR催化剂的设计铺平道路。更广泛的影响，我们建议进行系统的，多学科的研究工作，调查原子水平的相互作用的Au，Cu，Pt，Pd与二氧化铈，氧化锆，或氧化锌的两个反应的利益生产的氢燃料电池，即水煤气变换和甲醇蒸汽重整反应。从这些系统中获得的知识对其他与清洁能源密切相关的重要反应具有机械和实践意义，包括来自化石燃料或生物质的其他含氧化合物的加工。来自塔夫茨大学化学工程和化学、威斯康星州化学工程和BNL化学的跨学科专家团队已经为这个项目组装起来。在跨学科的努力结束时，我们将回答原子分散的金属，金属簇，并支持表面合金的二氧化铈，氧化锆，或氧化锌纳米粒子的活性和选择性的关键问题，并能够提供合理的设计，为实际的催化剂制备。这些材料将用于燃料和生物燃料加工，并作为燃料电池应用的阳极催化剂和薄膜。因此，这些发现的影响将导致更好的电力系统设计。这里涉及的每个学科都有其他一些切实的好处：催化剂合成的新方法，对传感器，燃料电池组件和催化剂重要的纳米级特定材料特性;以及低成本燃料和化学品生产的新催化剂设计。一个总的好处是，将是一个合理设计催化剂的模板，这些催化剂来自该项目的跨学科活动。在我们的实验室里，我们定期与工业界的同事交换信息，这已经成为一种传统。在这个项目中，我们计划让工业界的同事作为技术顾问，既为科学，也可能为技术转让。该提案的跨学科性质显然影响到研究生和研究生研究员的教育。该项目还计划对BNL的年轻研究人员进行广泛培训。大量女学生将参与该项目，塔夫茨大学本科生暑期奖学金计划将用于招募其他代表性不足的群体。将通过出版物、专题介绍和会议等正常渠道传播这项工作。为了实现真正广泛的传播，将创建一个网站作为纳米催化和能源网站的一部分，以促进这项工作，作为教育资源和招聘工具。