EAGER: Revisiting Catalyst Design in Heat-Exchanger Microreactors

摘要：Wilhite，Benjamin Institution：Texas A&Amp；M Proposal Number：1319142标题：EIGER：重访换热微反应器中的催化剂设计天然气(甲烷)高效催化转化为氢气和/或合成气对于新兴清洁能源行业和现有的石化和天然气市场来说，仍然是一个严峻的挑战。开发可从天然气中操作的高效、中型高纯度氢气发生器将使现有的天然气资源能够立即转换为零排放的氢燃料。高效地将甲烷转化为合成气(随后转化为合成原油)的成本效益技术的实现，促进了丰富的天然气直接替代日益减少的石油资源，而对现有石化基础设施的破坏最小。能够实现甲烷放热燃烧和吸热蒸汽重整的高效热耦合的换热器微反应器为应对这些挑战提供了一个强大的平台。目前的热交换器微反应器设计采用直接放置在微通道壁上的薄催化洗涤涂层，使得吸热(水蒸气重整)和放热(燃烧、部分氧化)过程之间的热传递除了预期的传热介质(即微反应器壁)外，还通过两种催化膜之间的传导发生。这代表着与催化剂颗粒设计的细微但显著的偏离，因为可以从催化剂膜的中心提供或带走热量(与颗粒设计中存在的绝热中心条件相反)。到目前为止，热交换器微反应器采用了均匀薄的催化膜，以防止任何内部热阻或传质阻力的形成。Pio？S等人在膜微反应器设计领域的研究结果表明，在催化剂膜中引入显著的传质阻力可以提供系统整体性能的突破。这是一项为期12个月的探索性工作，目的是确定在换热器-微反应器中使用的催化剂膜引入显著热传递阻力的非常规催化剂设计是否能够在催化剂和热利用方面实现突破。这一假设将通过详细的计算流体动力学(CFD)模拟的工业辐射微反(RMR)正在开发的这一应用。用于精炼和验证CFD模拟的实验数据将由Power&Amp；Energy，Inc.提供，以支持这一基础研究工作。这项研究既新颖又高风险/高收益，因为PI打算在催化剂和反应器尺度上引入显著的传热阻力，以操纵反应传输现象。因此，设计战略与旨在最大限度地减少运输限制的传统催化剂和反应器设计原则以及热交换器微反应器设计的当前实践形成鲜明对比。智力优势：根据本奖项获得的基本知识预计将对微反应器和过程强化社区具有广泛价值。基础分析和设计模拟将通过在强调反应堆设计的同行评议研究期刊上发布，包括《化学工程杂志》、《化学工程科学》、《工业与工程化学研究》和《AIChE期刊》。研究结果还将通过在ACS和AIChE全国会议上的研究报告传播。更广泛的影响：天然气或沼气制氢方面的突破，直接支持具有相应环境和经济优势的可持续能源经济的发展。氢气或合成气技术的进步满足了石化和天然气行业的关键工业需求，并具有相应的经济优势。

ABSTRACTPI: Wilhite, Benjamin Institution: Texas A&MProposal Number: 1319142Title: EAGER: Revisiting Catalyst Design in Heat-Exchanger MicroreactorsThe efficient catalytic conversion of natural gas (methane) to hydrogen and/or synthesis gas remains a critical challenge for both emerging clean energy industries and existing petrochemical and natural gas markets. Development of efficient, meso-scale high-purity hydrogen generators operable from natural gas would allow immediate conversion of existing natural gas resources to an emission-free hydrogen fuel. Realization of cost-effective technologies for efficiently converting methane to synthesis gas (for subsequent conversion to synthetic crude oil) facilitates the direct substitution of abundant natural gas for dwindling petroleum resources with a minimal disruption to existing petrochemical infrastructure. Heat-exchanger microreactors, capable of efficient thermal coupling of exothermic methane combustion with endothermic steam reforming provide a robust platform for meeting these challenges. Current heat-exchanger microreactor designs employ thin catalytic washcoatings placed directly over the microchannel wall, such that heat transfer between endothermic (steam reforming) and exothermic (combustion, partial oxidation) processes occur via conduction across both catalyst films, in addition to the intended heat transfer medium (i.e. microreactor wall). This represents a subtle yet significant departure from catalyst pellet designs, as heat may be supplied or removed from the center of the catalyst film (as opposed to the adiabatic center condition present in pellet designs). To date heat exchanger micoreactors have employed uniformly thin catalyst films to prevent the development of any internal heat- or mass-transfer resistances. The PI?s previous research results in the field of membrane microreactor design have illustrated that introducing significant mass transport resistances in catalyst films can provide breakthroughs in overall system performance.This is a 12-month exploratory effort to determine whether unconventional catalyst designs aimed at introducing significant heat-transport resistances to catalyst films employed in heat exchangermicoreactors can achieve breakthroughs in catalyst and heat utilization. This hypothesis will be explored through detailed computational fluid-dynamic (CFD) simulations of an industrial radialmicroreactor (RMR) under development for this application. Experimental data for refining and validating CFD simulations will be provided by Power & Energy, Inc. in support of this fundamental research effort. The research is both novel and high-risk / high-gain, as the PI intends to introduce significant heat-transfer resistances at the catalyst- and reactor-scales to manipulate reaction-transport phenomena. The design strategy thus stands in contrast to traditional catalyst and reactor-design principles aimed at minimizing transport limitations, as well as current practices in heat exchanger microreactor design.Intellectual Merit: Fundamental knowledge gained under this award is expected to be of broad value to the microreactor and process-intensification community. Fundamental analysis and design simulations will be disseminated through publication in peer-reviewed research journals emphasizing reactor design, including Chemical Engineering Journal, ChemicalEngineering Science, Industrial & Engineering Chemistry Research and AIChE Journal. Findings will also be disseminated through research presentations at ACS and AIChE national meetings.Broader Impact: Breakthroughs in hydrogen production from natural gas, or biogas, directly support the development of a sustainable energy economy with commensurate environmental and economic advantages. Advances in hydrogen or synthesis gas technologies meet critical industrial needs in the petrochemicals and natural gas industries, with commensurate economic advantages.