Ethanol Transport and Chemistry in Solid Oxide Fuel Cells

Biofuels are receiving significant interest as a source for sustainable, locally produced hydrocarbon fuels. While solid-oxide fuel cells (SOFCs) can operate efficiently on biomass fuel streams, their use can prove problematic if process conditions are not carefully monitored, as carbon-deposit formation presents a significant risk. In this study, we examine the chemistry and transport processes underway when SOFC anodes are exposed to ethanol-steam mixtures. Through use of a unique Separated-Anode Experiment, this study decouples anode chemistry processes from charge-transfer, cathode-activation, and other electrochemical processes in an effort to focus on ethanol decomposition in SOFC environments. Experiments are combined with numerical simulations that include Dusty-Gas transport modeling within the anode pore structure, and elementary, multi-step heterogeneous and homogeneous chemical kinetics mechanisms representing fuel conversion within the anode. Process windows for deposit-free operation are postulated, and alternate anode architectures that minimize the risk of deposit formation are discussed.