Film Boiling with Chemical Reaction: catalytic decomposition and hydrogen production in a self-assembled reactor

薄膜沸腾化学反应：自组装反应器中的催化分解和氢气生产

• 批准号: 0500015
• 负责人: Charles Avedisian
• 金额: $ 33.91万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-15 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0500015&HistoricalAwards=false
• 关键词: Film; Boiling; Chemical; Reaction; catalytic

Film Boiling with Chemical Reaction: Catalytic decomposition and hydrogen production in a self-assembled reactorPI: C. Thomas Avedisian, Cornell UniversityCo-PI: Wing Tsang, National Institute of Standards and TechnologyAbstractThe proposal was received as an unsolicited submission to the Chemical and Transport Systems Division and was subsequently transferred to the Thermal Transport and Thermal Processing Program. This research concerns developing a new type of chemical reactor for studying catalytic decomposition of organic liquids. The reactor concept is based on high temperature catalytic reaction in a subcooled liquid in which film boiling is established on a heated, catalyst-coated, surface such as a horizontal tube that is our baseline configuration. The reactor volume is the vapor film surrounding the tube surface, and it is self-assembled in the sense of forming naturally as a consequence of establishing the film-boiling regime by heat transfer from the tube to the surrounding liquid. Control variables for creating the reactor are the tube wall temperature and tube diameter, both of which also effect product yields. The research will demonstrate operation of the reactor with conversion of methanol to hydrogen and carbon monoxide on a catalyst-coated tube immersed in a pool of sub-cooled methanol. A catalyst is required to drive the reaction at operational temperatures. The reactor will operate as follows. In film boiling, liquid will evaporate and diffuse across the film to the tube surface where reactant molecules are adsorbed and react, and vapor is simultaneously transported around the tube and combines with products that diffuse from the tube surface into the vapor film. The gas mixture containing product and reactant vapors will be expelled from the system in the form of bubbles that percolate from the top of the tube. The intellectual merit of the study is found in the development of the enabling technology for film boiling with chemical reaction. Film boiling has not previously been used in a process to deliberately promote chemical reaction for a useful purpose, as a means to produce hydrogen, as a process to evaluate catalyst performance, or to measure rate constants associated with performance. The research of this project will examine this potential. A test cell will be fabricated to contain a submerged tube coated with a catalyst (e.g., platinum black for methanol conversion) and be designed to measure product yields. The data will be used in an analysis of film boiling with chemical reaction to extract kinetic rate data from product yield measurements. The research team consists of two PIs with experience in phase change processes and chemical kinetics. The broader impacts of the project relate to the variations and multiple functions envisioned for the film boiling reactor concept. These include as a tool to study reaction engineering and as a portable means to produce hydrogen from organic liquids including biomass-derived fuels. The geometry selected for study is a horizontal tube coated with a catalyst because it is amenable to modeling and extending film boiling theory to chemical reaction; other physical configurations for a film boiling reactor are envisioned, including flat plates, tube arrays and scale-down to include a lab-on-a-chip concept. With film boiling on the outside of a tube, the catalyst can be visually observed throughout reaction which contrasts with other reactor designs where the high temperature reaction zone is visually inaccessible and performance is measured by knowing only what went in and what came out. As a means to produce hydrogen, the intent will be to show that hydrogen can be produced from the comparatively small physical volume of the vapor film surrounding the tube in the film boiling regime. With the tube surface being hot to drive surface reactions and the liquid/vapor interface cold, the problem of high temperature containment of reactant usually associated with other reactor concepts (e.g., packed bed reactor) is eliminated.

化学反应薄膜沸腾：在自组装反应器中催化分解和生产氢气PI：C.Thomas Avedisian，康奈尔大学合办PI：WING曾，国家标准与技术研究所摘要该提案是作为主动提交给化学和运输系统部门的，随后被转移到热运输和热处理项目。本研究旨在开发一种用于研究有机液体催化分解的新型化学反应器。该反应器的概念是基于过冷液体中的高温催化反应，其中薄膜沸腾建立在加热的、涂有催化剂的表面上，例如我们的基线配置水平管。反应器体积是包围在管子表面的汽膜，它是通过从管子到周围液体的热传递建立膜沸腾状态而自然形成的自组装。创建反应器的控制变量是管壁温度和管径，这两个因素也会影响产品产量。这项研究将演示该反应器的操作，将甲醇转化为氢和一氧化碳，在浸泡在过冷甲醇池中的催化剂涂层管上进行。在操作温度下，需要催化剂来推动反应。该反应堆将按如下方式运行。在薄膜沸腾中，液体将蒸发并扩散到管子表面，在那里反应物分子被吸附和反应，蒸汽同时在管子周围传输，并与从管子表面扩散到蒸汽膜的产品结合。含有产物和反应物蒸汽的气体混合物将以气泡的形式从系统中排出，这些气泡从管子的顶部渗出。这项研究的智力价值体现在化学反应膜沸腾使能技术的发展中。膜沸腾以前从未被用于为了有用的目的而故意促进化学反应的过程中，作为生产氢气的一种手段，作为评估催化剂性能的过程，或测量与性能相关的速率常数。这个项目的研究将检验这一潜力。一个测试单元将被制造成包含一个涂有催化剂(例如，用于甲醇转化的铂黑)的浸没管，并被设计成测量产品产量。这些数据将用于膜沸腾与化学反应的分析，以从产品产量测量中提取动力学速率数据。研究团队由两名具有相变过程和化学动力学经验的PI组成。该项目的更广泛影响涉及膜沸腾反应器概念的变化和设想的多种功能。其中包括作为研究反应工程的工具和从有机液体(包括生物质衍生燃料)生产氢气的便携手段。选择用于研究的几何结构是涂有催化剂的水平管，因为它可以建模并将膜沸腾理论扩展到化学反应；还设想了膜沸腾反应器的其他物理结构，包括平板、管阵列和缩小到包括芯片实验室的概念。通过管子外部的薄膜沸腾，可以在整个反应过程中直观地观察到催化剂，这与其他反应器设计不同，在其他反应器设计中，高温反应区是不可见的，性能是通过只知道进出什么来衡量的。作为生产氢气的一种手段，其目的将是表明，在膜沸腾状态下，可以从围绕管子的相对较小的蒸汽膜的物理体积中生产氢气。由于管子表面是热的，以驱动表面反应，而液/气界面是冷的，因此消除了通常与其他反应器概念(例如，填充床反应器)相关的反应物高温遏制问题。