| Abstract
| - An integrated internal reforming solid oxide fuel cell (IIR-SOFC), in which the reformer is in good thermalcontact with the SOFC, is an energy-efficient mode of operation. However, the rapid, highly endothermicmethane steam reforming (SMR) reaction causes undesirable local cooling at one point or another within theSOFC system. Earlier simulation studies had indicated several system modifications that could eliminate thisproblem. Accordingly, experimental studies were carried out to find a suitable catalyst and reactor configurationthat lowered the rate of the reforming reaction while retaining activity in the face of potential carbon depositionor sulfur poisoning. A 0.5 wt % Rh/CeZrO2 has been identified as a catalyst that could provide the featuresthat are suitable for the application in an IIR-SOFC. The catalyst showed good activity and stability towardthe SMR. Kinetic studies provided overall information that was incorporated into the SOFC model developedto investigate its feasibility as the reforming catalyst. A further set of experiments investigated the use of theRh/CeZrO2 catalyst as the thin washcoat on the wall of the reformer. It was demonstrated that the coatedcatalyst had a suitably reduced but stable activity. It was shown that a barrier material (ZrO2) could also beused to lower the catalyst activity and provide a mass transfer limited operation. The barrier material couldbe used to create a catalyst activity profile along the length of the reactor. By the addition of small amountsof oxygen to the feed, methane oxidation could be used to reduce the overall endothermicity of the reformingprocess; this can serve to improve the temperature profile within the reformer. Simulations indicated thattypical methane-to-oxygen ratios of 10:1 to 20:1 were most effective. From the results obtained, Rh/CeZrO2has demonstrated its potential as the reforming catalyst in a SOFC, especially in a coated-wall configuration.The experimental results demonstrated that the configurations investigated by the simulation were achievablein practice.
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