GOALI: Collaborative Research: Phase Behavior and Reactivity of a Hygroscopic System

目标：协作研究：吸湿系统的相行为和反应性

• 批准号: 0755253
• 负责人: Karl Johnson
• 金额: $ 26.87万
• 依托单位: University of Pittsburgh
• 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: 2008-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0755253&HistoricalAwards=false
• 关键词: GOALI; Collaborative; Research; Phase; Behavior

CBET-0755253Johnson This project is a fundamental study of the mechanisms involved in the hydrolysis reaction of sodium borohydride with water. In its simplest form the reaction is written as NaBH4 + H2O = 2 H2 + NaBO2. Practically, NaBH4 hydrolysis is an option for hydrogen storage for fuel cells. The reaction is significant scientifically because of the complexity of the hygroscopic NaBH4 surface and the role of water sorption on the reaction kinetics. Despite a long history of research and development, the basic mechanism of these steps is not understood on a molecular basis. In particular, recent experiments at the University of South Carolina show that quantitative yields of hydrogen are obtained when the reaction is conducted by contacting water vapor with the hydride. The kinetic limitations associated with aqueous solution hydrolysis are not present in the gas phase reaction pathway. However, the reaction yields are very sensitive to temperature and gas phase composition. This evidence leads to the hypothesis that the first step in the reaction pathway is sorption of water vapor onto the surface; subsequently the reaction proceeds only when sufficient water has adsorbed to form a thin liquid layer. The goal of this project is to explore this hypothesis by developing a fundamental, molecular level understanding of the hydrolysis reaction. The specific objectives are (1) to quantify the reaction envelope (space of temperature, pressure, and composition of water vapor) that allows water sorption and the hydrolysis reaction to occur; (2) to obtain real-time, in situ Raman spectra during the course of the reaction to shed insight on the molecular events associated with adsorption and reaction, and (3) to understand and interpret experimental results through molecular simulation of the NaBH4 surface and the adsorption and initial reaction of water vapor with the surface. This is a collaborative, GOALI project that partners the University of South Carolina, the University of Pittsburgh, and Millennium Cell Inc. of Eatontown, NJ. Experimental studies will be conducted at South Carolina, while molecular simulations will be done at Pitt. Millennium Cell, Inc. is a small business that manufactures hydrogen storage and generation systems based on NaBH4. This project continues an existing intellectual collaboration with South Carolina, and extends it to the University of Pittsburgh. Intellectual Merit: This project represents an attempt at molecular level understanding of this particular hydrolysis reaction, which is one of a larger class of possible hydrolysis reactions. The PIs expect new scientific insights into the structure and reactivity of the highly hygroscopic hydride surface, and of the mechanisms of adsorption and reaction. Experimentally and theoretically this is a challenging system because of the near simultaneous reaction that follows water adsorption. Experimental data on the adsorption phenomenon will be modeled using first principles methods. The real-time Raman spectra will provide insight into the reaction that in turn will inform the molecular simulations. Broader Impacts: Study of this reaction has immediate implications for development of practical hydrogen storage systems. The GOALI program will enhance interaction of these two leading laboratories by involving industrial scientists and engineers. In addition to regular communications and dissemination of research results, the partners will engage in periodic site visits. Millennium Cell Inc. will annually host a graduate student on an industrial internship, strengthening the flow of scientific and industrial information for the project. This basic science project has been developed from the environment created by the NSF-funded Industry/University Cooperative Research Center for Fuel Cells, located at the University of South Carolina.

CBET-0755253Johnson 该项目是对硼氢化钠与水的水解反应机理的基础研究。该反应最简单的形式可写为 NaBH4 + H2O = 2 H2 + NaBO2。实际上，NaBH4 水解是燃料电池储氢的一种选择。由于吸湿性 NaBH4 表面的复杂性以及水吸附对反应动力学的影响，该反应具有重要的科学意义。尽管研究和开发历史悠久，但这些步骤的基本机制尚不清楚。特别是，南卡罗来纳大学最近的实验表明，当通过水蒸气与氢化物接触进行反应时，可以获得定量的氢气产率。气相反应途径中不存在与水溶液水解相关的动力学限制。然而，反应产率对温度和气相组成非常敏感。这一证据导致了这样的假设：反应途径的第一步是水蒸气吸附到表面上；随后，只有当吸收了足够的水以形成薄液体层时，反应才会进行。该项目的目标是通过对水解反应进行基本的分子水平理解来探索这一假设。具体目标是（1）量化允许水吸附和水解反应发生的反应范围（温度、压力和水蒸气成分的空间）； (2) 获得反应过程中的实时原位拉曼光谱，以深入了解与吸附和反应相关的分子事件；(3) 通过 NaBH4 表面的分子模拟以及水蒸气与表面的吸附和初始反应来理解和解释实验结果。这是一个 GOALI 协作项目，由南卡罗来纳大学、匹兹堡大学和新泽西州伊顿敦的 Millennium Cell Inc. 合作。实验研究将在南卡罗来纳州进行，分子模拟将在皮特大学进行。 Millennium Cell, Inc. 是一家小型企业，生产基于 NaBH4 的储氢和发电系统。该项目继续与南卡罗来纳州现有的智力合作，并将其扩展到匹兹堡大学。智力优点：该项目代表了在分子水平上理解这种特定水解反应的尝试，该反应是一大类可能的水解反应之一。 PI 期望对高吸湿性氢化物表面的结构和反应性以及吸附和反应机制有新的科学见解。从实验和理论上来说，这是一个具有挑战性的系统，因为水吸附后几乎同时发生反应。吸附现象的实验数据将使用第一原理方法进行建模。实时拉曼光谱将提供对反应的深入了解，从而为分子模拟提供信息。更广泛的影响：该反应的研究对实用储氢系统的开发具有直接影响。 GOALI 计划将通过工业科学家和工程师的参与来加强这两个领先实验室的互动。除了定期沟通和传播研究成果外，合作伙伴还将定期进行实地考察。 Millennium Cell Inc. 每年都会接待一名研究生进行工业实习，加强该项目的科学和工业信息流动。该基础科学项目是在美国国家科学基金会资助的南卡罗来纳大学燃料电池工业/大学合作研究中心创建的环境中开发的。