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In this paper, strategies for biogas reforming and their ensuing effects on solid oxide fuel cell (SOFC) performance are explored. Synthesized biogas (65% CH4 + 35% CO2) fuel streams are reformed over a rhodium catalyst supported on a porous α-alumina foam. Reforming approaches include steam reforming and catalytic partial oxidation (CPOX) utilizing either air or pure oxygen as the oxidant. A computational model is developed and utilized to guide the specification of reforming conditions that maximize both CH4 and CO2 conversions. Model predictions are validated with experimental measurements over a wide range of biogas-reforming conditions. Higher reforming temperatures are shown to activate the biogas-borne CO2 to enable significant methane dry-reforming chemistry. Dry reforming minimizes the oxidant-addition needs for effective biogas conversion, potentially decreasing the thermal requirements for reactant heating and improving system efficiency. Such high-temperature reforming conditions are prevalent during CPOX with a pure-O2 oxidant. While CPOX-with-O2 reforming is highly exothermic, the endothermicity of dry-reforming chemistry can be exploited to ensure that catalyst temperatures do not reach levels which cause catalyst sintering and degradation. SOFC electrochemical performance under biogas reformate is shown to vary substantially with reforming approach. Cell operation under CPOX-with-O2 reformate is found to be comparable to that under humidified hydrogen.

In this paper, several strategies for biogas reforming and their ensuing effects on solid-oxide-fuel-cell performance are explored. Synthesized biogas (65% CH4 + 35% CO2) fuel streams are reformed over a rhodium catalyst supported on a porous alumina-foam support. Reforming approaches include steam reforming and catalytic partial oxidation utilizing either air or pure oxygen as the oxidant. A computation model is developed and utilized to guide definition of reforming conditions that maximize both CH4 and CO2 conversion. Model predictions are validated with experimental measurements over a wide range of biogas-reforming conditions. It is shown that higher reforming temperatures activate the CO2 in the biogas through dry-reforming reactions. Such dry-reforming chemistry leads to high CO content in the reformate streams, extensive water-gas shift reactions within the SOFC anode structure, and high SOFC power density.

Efforts to address deposit formation in hydrocarbon-fueled solid oxide fuel cells have motivated development of advanced anode materials and architectures. The Separated Anode Experiment has been developed to decouple anode internal-reforming processes from electrochemical processes, providing a unique method of evaluating novel anodes and supports. Here, we present experimental and numerical results and compare performance of a Ni-YSZ anode support to a porous metallic support. Additionally, a computational model is developed and utilized as a tool in understanding gas transport and internal reforming processes, and for optimization of anode morphological design.

This paper presents an analysis of the gas‐transport and methane internal‐reforming characteristics of two commercially developed solid‐oxide fuel cell (SOFC) anode supports. The anode supports are fabricated by CoorsTek, Inc. (Golden, CO, USA) and Risø‐DTU (Lyngby, Denmark). While both supports are ceramic‐metallic composites of yttria‐stabilized zirconia and nickel (Ni‐YSZ), their morphological structures and thicknesses are quite different. The CoorsTek support is thick and displays an open microstructure, while the Risø‐DTU support is fairly thin with a tighter morphology. These micro‐ and macrostructural differences lead to significant variations in gas transport and methane internal‐reforming chemistry within the porous support structures that directly affect cell performance. In this study, anode‐support performance is analyzed using the separated anode experiment, a unique tool that decouples anode‐support thermal‐chemistry processes from electrochemical processes typically underway during SOFC operation. Experimental results are interpreted using a detailed computational model. Gas transport is higher in the CoorsTek support despite being nearly five times thicker than the Risø‐DTU support. The methane internal‐reforming performance of the Risø‐DTU anode, however, speaks to its tighter microstructure and resulting higher catalytic surface area. These results highlight the dependence of support performance on macro‐ and microstructure in terms of gas transport and internal‐reforming chemistry.