EAGER: Low-temperature Coupling of Methane Surrogates over Single Atom Catalysts: Elucidation of Elementary Reactions for C-C Bond Formation

EAGER：单原子催化剂上甲烷替代物的低温偶联：阐明 C-C 键形成的基本反应

• 批准号: 2328552
• 负责人: Robert Rioux
• 金额: $ 30万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2328552&HistoricalAwards=false
• 关键词: EAGER; Low; temperature; Coupling; Methane

Methane is a potent greenhouse gas and the chief component of natural gas. Presently, most natural gas is combusted resulting in emissions of carbon dioxide (CO2) – also a greenhouse gas. The project investigates an alternative approach to methane utilization employing a reaction known as non-oxidative coupling of methane (NOCM). NOCM avoids the formation of CO2 by converting the methane primarily to ethylene and aromatic compounds – important precursors to a wide range of chemical products. While the reaction is not new, its potential application has been limited by incomplete understanding of the complex reaction chemistry which, in turn, complicates the design effective NOCM catalysts. To overcome those limitations, this EArly-concept Grant for Exploratory Research (EAGER) project examines the elementary reactions that occur during NOCM over a novel class of catalysts known as single-atom catalysts (SACs) using alkyl halide methane surrogate molecules. The potential of NOCM to produce alkenes and aromatics from fossil-derived and biological methane resources represents a stop-gap solution to fully carbon-neutral approaches to the manufacture of chemicals and fuels. NOCM is a highly endothermic reaction, necessitating the use of high temperatures, which leads to a significant impact of gas-phase chemistry on the observed product distribution of the surface-catalyzed reaction. The project will investigate reactions of alkyl halide molecular surrogates of methane. The surrogates allow for low temperature reactivity, thus eliminating complications associated with gas-phase chemistry contributions. The project examines the impact of SAC structure and composition on the ability to form carbon-carbon bonds to produce alkenes of varying size and aromatics. Specifically, three aspects of C-C bond formation chemistry on SACs will be investigated at moderate temperatures (200 to 400 degrees Celsius) where surface reactions prevail: (i) coupling between -CH3(ads) and =CH2(ads) surface fragments; (ii) coupling between -CH3(ads) surface fragments and C2 species (either -C2H5(ads) or C2H4(g), a product of NOCM) and (iii) surface-catalyzed aromatic formation through cyclotrimerization chemistry. The three experimental tasks will focus on quantifying reaction rates, selectivity, and mechanistic details of C-C coupling using isotopically labeled substrates. A fourth aim will focus on density functional theory-based discovery of SACs for C-C bond formation, and the development of microkinetic models for promising SAC candidates. The catalysts will be characterized before and after reaction by complementary techniques to assess the single atom nature of the catalysts and the impact of NOCM chemistry on the catalyst structure.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

甲烷是潜在的温室气体，也是天然气的主要组成部分。目前，大多数天然气是燃烧的，导致二氧化碳（CO2）的排放 - 也是温室气体。该项目使用一种称为甲烷（NOCM）的非氧化偶联的反应来研究甲烷利用的另一种方法。 NOCM通过将甲烷原发性转化为乙烯和芳香族化合物（重要的前体），从而避免了CO2的形成。虽然该反应并不是什么新鲜事物，但由于对复杂反应化学的了解不完全了解，其潜在应用又受到限制，而复杂的反应化学反应又使设计有效的NOCM催化剂变得复杂。为了克服这些局限性，这种探索性研究的早期概念赠款（急切）项目考试在NOCM期间发生的基本反应是在一种新型的催化剂中，使用纯卤代甲烷替代物分子，称为单原子催化剂（SACS）。 NOCM从化石衍生和生物甲烷资源中产生烯烃和芳香剂的潜力代表了完全碳和燃料制造化学品和燃料的完全含量差异解决方案。 NOCM是一种高度吸热的反应，是使用高温所必需的，这导致气相化学对观察到的表面催化反应的产物分布的显着影响。该项目将研究甲烷烷基卤化物分子替代物的反应。替代物允许低温反应性，从而消除了与气相化学贡献相关的并发症。该项目研究了SAC结构和组成对形成碳碳键的能力以产生不同大小和芳香剂的烯烃的能力。具体而言，将在中等温度（200至400摄氏度）上研究SAC上C -C键形成化学的三个方面，其中表面反应占上风：（i）-CH3（ADS）和= CH2（ADS）和= CH2（ADS）表面​​片段之间的耦合； （ii）-CH3（ADS）表面​​碎片与C2种（-C2H5（ADS）或C2H4（G），NOCM的产物）和（III）表面催化的芳族形成之间的耦合。这三个实验任务将集中于使用同位素标记的底物量化C-C耦合的反应速率，选择性和机理细节。第四个目标将集中于基于密度功能理论的基于C-C键形成的SAC的发现，以及为Promise SAC候选者的微动力学模型的开发。催化剂将通过完善技术进行反应前后的表征，以评估催化剂的单个原子性质以及NOCM化学对催化剂结构的影响。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子和更广泛的影响审查审查标准来通过评估来诚实地通过评估来诚实地支持。