Electrochemical reforming of CH4−CO2 mixed gas using porous Gd-doped ceria electrolyte with Cu electrode

Abstract This paper reports on the composition and flow rate of outlet gas and current density during the reforming of CH 4 with CO 2 using three different electrochemical cells: cell A, with Ni−GDC (Gd-doped ceria: Ce 0.8 Gd 0.2 O 1.9 ) cathode/porous GDC electrolyte/Cu−GDC anode, cell B, with Cu−GDC cathode/ porous GDC electrolyte/Cu−GDC anode and cell C, with Ru−GDC cathode/ porous GDC electrolyte/ Cu−GDC anode. In the cathode, CO 2 reacts with supplied electrons to form CO fuel and O 2− ions (CO 2 +2e − →CO+O 2− ). Too low affinity of Cu cathode to CO 2 in cell B reduced the reactivity of the CO 2 with electrons. The CO fuel, O 2− ions and CH 4 gas were transported to the anode through the porous GDC mixed conductor of O 2− ions and electrons. In the anode, CH 4 reacts with O 2− ions to produce CO and H 2 fuels (CH 4 +O 2− →2 H 2 +CO+2e − ). The reforming efficiency at 700−800 °C was lowest in cell B and highest in cell A. The Cu anode in cells A and C worked well to oxidize CH 4 with O 2− ions (2Cu+O 2− →Cu 2 O+2e − , Cu 2 O+CH 4 →2Cu+CO+2H 2 ). However, a blockage of the outlet gas occurred in all the cells at 700−800 °C. The gas flow is inhibited due to a reduction in pore size in the cermet cathode, as well as sintering and grain growth of Cu metal in the anode during the reforming.