Electrochemical reforming of CH4-CO2 mixed gas using porous yttria-stabilized zirconia cell

Abstract

Flow rate and compositions of outlet gas and carbon deposition in the cell were studied upon the electrochemical reforming of 50% CH4-50% CO2 mixed gas using a cell of Ruyttria- stabilized zirconia (YSZ) anode/porous 8 mol%-YSZ electrolyte/ NiYSZ cathode system at 400800°C under 1.0V/cm of electric field strength. The supplied mixed gas of 9597% changed to H2 and CO fuels at 800°C (CH4 + CO2=2H 2 + 2CO). As a parallel reaction, pyrolysis of CH4 occurred over a Ni cathode to produce carbon powder in the cell (CH 4=C + 2H2), which decreased the flow rate of outlet gas at a high temperature. The above results were compared with the previously measured results with a porous Gd-doped ceria cell (mixed conductor of O 2- ions and electrons). In the GDC cell, a part of deposited carbon was removed as CO gas by the reaction with O2- ions formed from CO2 gas in the cathode (CO2 + 2e-=CO + O 2-, C + O2-=CO + 2e-) and the electrons produced were transported to the anode through the mixed conductor electrolyte film. © 2011 The Ceramic Society of Japan.