Oxidation Chemistry on Transition-Metal Doped Rare Earth Oxide Surfaces: Factors Determining Selectivity for the Oxidative Coupling of Methane

过渡金属掺杂稀土氧化物表面的氧化化学：决定甲烷氧化偶联选择性的因素

• 批准号: 1464765
• 负责人: Jason Weaver
• 金额: $ 51万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1464765&HistoricalAwards=false
• 关键词: Oxidation; Chemistry; Transition; Metal; Doped

Oxidation Chemistry on Transition-Metal Doped Rare Earth Oxide Surfaces - Factors Determining Selectivity for the Oxidative Coupling of MethaneIn this project, Drs. Jason Weaver and Helena Hagelin-Weaver at the University of Florida are investigating how transition-metal dopants modify the oxidation chemistry catalyzed by rare earth oxides (REOs), focusing particularly on the oxidation of hydrocarbons. Of particular interest is the use of metal-doped REOs as catalysts to efficiently promote the oxidative coupling of methane (OCM) to valuable two carbon (C2) products, while avoiding the complete oxidation of methane to carbon dioxide (CO2) and water (H2O). Developing a commercially viable OCM catalyst may enable the more effective utilization of natural gas resources, and thus have significant economic and environmental impacts. The project aims to advance the basic understanding of the selectivity of REO catalysts toward partial vs. complete oxidation reactions, and to enable rational approaches for designing metal-doped REO catalysts with desirable and adjustable properties. The ability to predictably modify the catalytic properties of an oxide by doping with different types of transition metals could afford significant flexibility in engineering catalysts for a wide-range of applications, including chemical synthesis, pollution control, and energy technologies. The project includes collaboration with researchers in Germany and Sweden that provide opportunities for graduate students to train in foreign laboratories and perform experiments at synchrotron facilities. Undergraduate students are also involved in this research, and underrepresented minorities are recruited through the investigators' participation in the University Minority Mentoring Program and in the Society of Women Engineers.In this project funded by the Chemical Catalysis Program, Drs. Jason Weaver and Helena Hagelin-Weaver at the University of Florida are investigating the properties of model rare earth oxide (REO) thin films and high surface-area catalysts, focusing particularly on systematically characterizing the effects that transition-metal doping have on the oxidation chemistry promoted by REO surfaces. REOs exhibit favorable catalytic performance for a diverse set of chemical transformations, including both partial and complete oxidation reactions. However, with ceria as a general exception, mechanistic details of REO surface chemistry and the factors determining catalytic selectivity are understood only to a limited extent. The project focuses on samaria and terbia as representative examples of effectively irreducible and reducible REOs, respectively, and on clarifying factors that promote the oxidative coupling of methane (OCM) to C2 products rather than complete oxidation. A combined approach is employed that involves model studies of transition-metal doped REO thin films in ultrahigh vacuum (UHV) and characterization of nano-crystalline REO catalysts under more realistic reactive conditions, with the aim to establish clear bridges in understanding across the materials and pressure divides. Key goals of the project are to develop new understanding of the relations between structural/electronic properties and the chemical selectivity of REO surfaces doped with different metals and to illuminate mechanistic aspects of the surface chemistry under realistic conditions. The project involves collaboration with researchers in Germany and Sweden and provides opportunities for students to train in the foreign laboratories and perform experiments at synchrotron facilities. Undergraduate students are also involved in this research, and underrepresented minorities are recruited through the PI's and co-PI's participation in the University Minority Mentoring Program and in the Society of Women Engineers.

过渡金属掺杂的稀土氧化物表面的氧化化学 - 决定甲烷蛋白氧化偶联的因素，该项目的氧化偶联。佛罗里达大学的Jason Weaver和Helena Hagelin Weaver正在研究如何修饰稀土氧化物（REOS）催化的氧化化学方法，特别是尤其着重于碳氢化合物的氧化。特别令人感兴趣的是将金属掺杂的REO用作催化剂，以有效地促进甲烷（OCM）的氧化偶联到有价值的两种碳（C2）产品，同时避免将甲烷完全氧化为二氧化碳（CO2）和水（H2O）。开发商业上可行的OCM催化剂可能可以更有效地利用天然气资源，从而产生重大的经济和环境影响。该项目旨在促进对REO催化剂对部分与完全氧化反应的选择性的基本理解，并实现理性方法，以设计具有理想且可调节性能的金属掺杂REO催化剂。通过与不同类型的过渡金属掺杂氧化物的催化特性可以预测的能力可以为广泛应用的工程催化剂提供显着的灵活性，包括化学合成，污染控制和能量技术。该项目包括与德国和瑞典的研究人员的合作，为研究生提供了在外国实验室培训并在同步基金设施进行实验的机会。本科生还参与了这项研究，并且通过调查人员参与大学少数民族指导计划和女工程师协会的招募人数不足。佛罗里达大学的Jason Weaver和Helena Hagelin Weaver正在研究模型稀土氧化物（REO）薄膜和高表面区域催化剂的特性，尤其着重于系统地表征过渡金属掺杂对REO表面促进的氧化化学的影响。 REO对各种化学转化，包括部分和完整的氧化反应表现出有利的催化性能。但是，对于陶瓷通常例外，仅在有限的程度上就可以理解REO表面化学的机理细节和确定催化选择性的因素。该项目的重点是撒玛利亚和terbia，是有效不可还原和可还原的REO的代表性例子，以及促进甲烷（OCM）与C2产物的氧化偶联的澄清因素，而不是完全氧化。采用了一种组合的方法，涉及在更现实的反应性条件下对超高真空（UHV）中过渡金属掺杂的REO薄膜进行模型研究，以及对纳米晶Reo催化剂的表征，旨在在材料和压力分配之间理解中明确的桥梁。该项目的关键目标是对结构/电子性质之间的关系以及带有不同金属掺杂的REO表面的化学选择性之间的关系进行新的了解，并在现实条件下阐明了表面化学的机械方面。该项目涉及与德国和瑞典的研究人员合作，并为学生提供了在外国实验室培训并在同步基金设施进行实验的机会。本科生还参与了这项研究，并且通过PI和Co-Pi参与大学少数民族指导计划以及女工程师协会的参与，招募了代表性不足的少数民族。