Development and study of self-sustained electrochemical promotion catalysts for hydrocarbon reforming

可再生碳氢化合物和含氧燃料重整制氢是未来氢经济的关键技术之一。催化重整是聚合物电解质燃料电池（PEFC）和固体氧化物燃料电池（SOFC）电源的关键工艺之一。最先进的技术，如短接触时间（SCT）催化剂和微通道（MC）重整器，不能同时满足每一个主要要求：高比功率密度、高效率、快速响应和启动、低成本和可接受的长期耐用性。这导致我们提出了碳氢化合物和氧合物重整催化剂的非传统概念。新概念利用选择性纳米或微尺寸电极上氧化和还原的远程耦合来实现催化重整反应的自我持续电化学促进（SSEP）。初步实验研究表明，无贵金属SSEP催化剂可在低至400℃的温度下实现重质液态烃的快速部分氧化重整，停留时间约5 ms，转化率高达98%，产氢率高达90%。此外，氧离子自持通量的可用性显著降低了碳沉积的倾向。该项目的最终目标是将该发现转化为高性能催化剂体系，验证催化剂设计的新概念，并探索催化剂优化的方法。本项目主要包括两个方面的工作：1)评估SSEP催化剂的催化活性和电化学促进作用，阐明组分材料的组成和性能的影响；2)建立连续统模型，分析SSEP催化剂的电化学促进POX重整性能，阐明SSEP的机理，寻找优化SSEP催化剂的途径。传统催化剂依赖于每个组分（催化剂、载体和启动子）在局部微观位点（~nm）的协同作用来实现催化。新概念催化剂可以使不同功能组分在较长距离（~mm）内偶联，从而大大提高本征催化活性。短寿命促进剂自持通量大，提高了催化活性相的活性和抗结焦性。这一概念也使得从纳米级到毫米级的功能型多尺度结构催化剂的设计和工程化成为可能，这与提高传质和传热特性的路线不同。因此，SSEP催化剂的概念将为催化重整技术带来突破。对功能组分的远程耦合进行实验研究和建模，不仅可以更好地了解新型催化剂的基本过程，而且可以为进一步优化催化剂提供指导。拟议的工作将(1)通过提供一种新的燃料处理系统，加强正在进行的聚合物电解质燃料电池和固体氧化物燃料电池的博士研究项目；（二）吸引、鼓励和支持优秀本科生攻读博士学位；(3)将改革和燃料加工信息整合到PI和Co-PI讲授的课程中；(4)将信息整合到常规的社区教育任务中；(5)促进女性和少数民族学生的教育。

CBET-0828379 ZhouHydrogen production from reforming renewable hydrocarbon and oxygenate fuels is one of the key technologies in future hydrogen economy. Catalytic reforming is one of the key processes in polymer electrolyte fuel cell (PEFC) and solid oxide fuel cell (SOFC) power sources. State-of-the-art technologies, such as short contact time (SCT) catalyst and micro-channel (MC) reformer, cannot simultaneously satisfy each of the major requirements: high specific power density, high efficiencies, fast response and start-up, low costs, and acceptable long-term durability. This leads us to propose a non-conventional concept of catalysts for hydrocarbon and oxygenate reforming. The new concept utilizes long-range coupling of oxidation and reduction on the selective nano- or micro-size electrodes to enable self-sustained electrochemical promotion (SSEP) of catalytic reforming reactions. Preliminary experimental study demonstrates that the precious metal-free SSEP catalysts can enable very fast partial oxidation reforming of heavy liquid hydrocarbons at temperatures as low as 400°C with a residence time ~ 5 ms, a high conversion rate (~98%) and high hydrogen yield (~90%). In addition, the availability of self-sustained flux of oxygen ions significantly reduces the propensity of carbon deposition. The ultimate objectives of the project are to turn the discovery into a high performance catalyst system, to validate the new concept of catalyst design, and to explore the methods for catalyst optimization. The proposed project will include two major activities: 1) To evaluate the catalytic activity and electrochemical promotion and to clarify the effects of the composition and properties of component materials and 2) To establish a continuum model to analyze electrochemically promoted POX reforming performances of the SSEP catalysts, to elucidate the mechanisms of SSEP, and to search for an avenue for optimizing the SSEP catalysts. The intellectual merits of the proposed activity Conventional catalysts rely on the coordinated effects of each of the components (catalysts, supports, and promoters) in a localized microscopic site (~nm) to enable catalysis. The new concept of catalysts can enable coupling of different functional components in a long distance (~mm), thereby greatly increasing intrinsic catalytic activity. The activity and resistance to coking of the catalytic active phases is enhanced with a large self-sustained flux of short-lived promoters. This concept also allows design and engineering of catalysts with functional multi-scale structure from nanometer range to millimeter range, which is different from the route of improving mass and heat transfer characteristics. Thus, the concept of SSEP catalysts will result in a breakthrough for the catalytic reforming technology. The experimental study and modeling of the long-range coupling of the functional components will not only provide better understanding of the basic processes in the new catalysts but also provide guidelines for further optimization of the catalysts. Broader impacts resulting from the proposed activity The proposed work will (1) enhance ongoing PhD research programs on polymer electrolyte fuel cell and solid oxide fuel cell by providing a novel fuel processing system; (2) attract, encourage, and support outstanding undergraduate students to pursue a PhD study; (3) integrate the information on reforming and fuel processing into curricula of the courses taught by the PI and Co-PI; (4) integrate the information into regular community education tasks; and (5) promote education of female and minority students.