Development of Catalyst- Assisted Direct Internal Reforming SOFCs

Direct internal reforming of hydrocarbon fuels allows significant improvements in fuel efficiencies of SOFC power generators by eliminating external reformer and heat exchangers as well as reducing air cooling requirements. While direct use of natural gas has been successfully demonstrated, high hydrocarbon fuels, such as gasoline and diesel have been more problematic due to coking on Ni-based SOFC anodes.
Catalyst assisted direct internal reforming SOFC single cells and short stacks directly operating under liquid fuels like simulated gasoline or logistic fuels are under development at FCT ultimately for high power-dense applications such as portable power generators and APUs.Planar cells utilizing ceramic anode supports and novel, flattened tubular segmented-in-series SOFCs are used with catalyst layers at the anodes for direct internal reforming. Single cells, having Ni-YSZ active anodes, YSZ electrolytes and LSM-YSZ cathode, exhibited stable operations with power densities of ~ 0.7 W/cm² at 800°C under iso-octane (a sulfur-free gasoline surrogate) with air or CO₂ + steam reforming gas. Use of sulfur-free diesel surrogates such as dodecane and tridecane has also been successfully demonstrated.
Results will be presented on the electrical tests and exhaust gas characterization using mass spectroscopy under various sulfur-free surrogate fuels simulating gasoline and diesel as well as commercially available sulfur-free fuel, such as Fischer-Tropsch synthetic diesel.

The thermal gradients are assessed for the internal reforming SOFCs with cell area > 20cm² and the effect of the catalyst variations on the thermal gradient are investigated. POX is used to simulate the start-up operations and CO₂ + steam reforming is used to simulate steady state operations under reforming using recycled exhaust gas.