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

膜沸腾与化学反应：自组装反应器中的催化分解和制氢。托马斯Avedisian，康奈尔大学合作PI：Wing Tsang，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计划。本研究旨在开发一种新型的化学反应器，用于研究有机液体的催化分解。反应器概念基于过冷液体中的高温催化反应，其中膜沸腾建立在加热的催化剂涂覆表面上，例如水平管，这是我们的基线配置。 反应器体积是围绕管表面的蒸汽膜，并且在自然形成的意义上，它是自组装的，作为通过从管到周围液体的热传递建立膜沸腾状态的结果。 用于产生反应器的控制变量是管壁温度和管直径，这两者也影响产物产率。 该研究将演示反应器的操作，将甲醇转化为氢气和一氧化碳，催化剂涂层管浸入过冷甲醇池中。在操作温度下需要催化剂来驱动反应。 反应堆将按如下方式运行。在膜沸腾中，液体将蒸发并穿过膜扩散到管表面，在管表面处反应物分子被吸附并反应，并且蒸气同时围绕管输送并与从管表面扩散到蒸气膜中的产物结合。 含有产物和反应物蒸气的气体混合物将以从管顶部渗出的气泡形式从系统中排出。该研究的智力价值在于开发了具有化学反应的膜沸腾使能技术。 薄膜沸腾以前没有用于为了有用目的而有意促进化学反应的方法中，作为生产氢气的手段，作为评价催化剂性能的方法，或测量与性能相关的速率常数。本项目的研究将考察这一潜力。 将测试单元制造成包含涂覆有催化剂的浸没管（例如，用于甲醇转化的铂黑），并设计用于测量产物产率。 这些数据将用于分析膜沸腾与化学反应，以从产品收率测量中提取动力学速率数据。 研究小组由两名在相变过程和化学动力学方面具有经验的PI组成。该项目更广泛的影响涉及到薄膜沸腾反应器概念的变化和多种功能。 这些包括作为研究反应工程的工具和作为从有机液体（包括生物质衍生燃料）生产氢的便携式手段。选择用于研究的几何形状是涂覆有催化剂的水平管，因为它适合于建模并将膜沸腾理论扩展到化学反应;设想膜沸腾反应器的其他物理配置，包括平板，管阵列和按比例缩小以包括芯片实验室概念。 在管的外部上的膜沸腾，催化剂可以在整个反应过程中被视觉观察，这与其他反应器设计形成对比，在其他反应器设计中，高温反应区是视觉上不可接近的，并且性能通过仅知道什么进入和什么出来来测量。 作为生产氢气的一种手段，其目的是表明，氢气可以从相对较小的物理体积的蒸汽膜周围的管在膜沸腾制度。 由于管表面是热的以驱动表面反应并且液体/蒸气界面是冷的，反应物的高温容纳的问题通常与其它反应器概念（例如，填充床反应器）。

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.