Operando Spectroscopic Studies of Solid Oxide Fuel Cell Operation Using Dimethyl Ether as an Alternative Fuel

Abstract

Dimethyl ether (DME) is an oxygen-containing fuel that is an attractive alternative to the reforming of light alkanes like CH4. Its higher volumetric exergy compared to CH4 yields comparable power densities to other fuels while decreasing its potential for performance degradation that results from coking. We have characterized an SOFC operating at 800 °C on DME using a suite of operando optical and ex post facto methods. Based on exhaust gas infrared spectroscopy, DME decomposes to CH4, C2H2, H2O, CO2, and CO. Electrochemical analysis indicates that under dry DME the maximum power output of an anode supported button cell Ni-YSZ SOFC is only 10% lower than under CH4 (where H content was matched in the fuel stream). FTIR analysis of the anode exhaust gas indicates an electrochemical response under galvanostatic conditions resulting in the consumption of both CH4 and C2H2 to form CO, CO2, and H2O. Operando near-infrared thermal imaging reveal more cooling at the anode surface with DME than CH4 resulting from increased endothermic cracking of CH4. Additional contributions to the cooling are possible from reforming reactions.