Direct Conversion of Oxygenated Fuels to Power Using Solid Oxide Fuel Cells

Over the last several decades, intermediate temperature (600-800°C) solid oxide fuel cells (ITSOFCs) have been developed that can generate electricity with very high efficiencies.  Although the high temperature of these fuel cells allows for power generation directly from carbonaceous fuels, current commercial nickel SOFCs cannot be run directly on carbonaceous fuels because the carbon quickly degrades the catalyst on the anode, or fuel side of the cell.  Recently, surface alloys have been made from nickel and tin that show improvements in the carbon tolerance of ITSOFCs on methane and iso-octane.   Concurrently, biofuels including ethanol and butanol have been developed from renewable plants and other biological sources which have a lower carbon footprint than conventional fossil fuels.  SOFCs run on these renewable fuels would create a highly efficient process to generate electricity with a small carbon footprint.

In this work, fuel cells with monometallic nickel and tin/nickel surface alloy anodes are made and tested with oxygenated fuels such as ethanol and butanol.  The performance and resistances across the fuel cells are monitored over time using chronoamperometry, linear sweep voltammetry, and electrochemical impedance spectroscopy.  The degradation of the fuel cell anodes is evaluated using scanning electron microscopy.  When run on ethanol, the nickel catalysts show changes in performance over time whereas the tin/nickel surface alloy catalysts have very stable performance.  The nickel catalysts also show more degradation over time than the alloy catalysts under the same conditions.