EAGER: Revisiting Catalyst Design in Heat-Exchanger Microreactors
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The 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.