Hydrogen 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.
Hydrogen 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) noble metal-based 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. The research is an experiemental and modeling study of a game-changing catalyst design method that not only removes the technical barriers but also provides a novel concept to the study of chemical catalysis. Novel self-sustained electrochemical promotion (SSEP) catalysts have been developed with following merits: 1) outperforming the conventional Ni-based and noble metal-based catalysts in a low temperature range (350-650°C); 2) enabling a ~100% conversion in the temperature range; 3) containing zero amount of noble metal; 4) mainly because of the low operating temperature, promising a very good long-term durability; and 5) because of use of non-noble metal and the low operating temperature, promising a significant reduction of energy loss and costs. It has been demonstrated that the novel design of the catalysts enables coordination/coupling among nanoscale anode and cathode phases via nanoscale conducting phases. The coordination/coupling among different functional components in a long-distance (~mm) greatly increases intrinsic catalytic activity. The concept of SSEP catalysts with coordinating functional components and structures from nanometer to millimeter ranges may be applied for many other important areas of renewable energy technology, including reduction of NOx from automobile emissions, conversion of carbon dioxide into fuels and value-added hydrocarbon products, and photo-electrochemical processes. In the life of this award, two PhD students graduated on this topic and one MS student graduated partially on this topic. Seven undergraduate students were hired to work on experimental and modeling tasks of the project. One of them was encouraged and selected to pursue a PhD. The PI has incorporated the materials into his summer scholar courses and has taught more than 50 high school students from Florida, other states, and other countries. The facilities acquired have been used for the PI’s teaching and research in other areas. Most of students benefited by the award were minority.
