Effect of methane concentration on reaction behavior in direct-methane solid oxide fuel cells with (Ce,Gd)O 2− x-impregnated FeCr layer for fuel processing

Abstract

A solid oxide fuel cell (SOFC) with a Ni-yttria-stabilized zirconia anode of 1 cm 2 area was set up with a porous disk of gadolinia-doped ceria-impregnated FeCr as a gas diffusion layer (GDL) under direct-methane feeding. In this setup of SOFC plus GDL, the tests at 800 °C and ambient pressure show that the current density, the methane conversion rate, the product formation rates, and the CO 2 selectivity increased with increasing methane concentration. The major reaction in the GDL is CO 2 reforming of methane to produce the syngas (CO plus H 2). The anodic electrochemical oxidation of CO from GDL results in an overall rate of CO 2 formation being much larger than that of CO formation. There is a synergy between the rate of reaction in the GDL and that over the anode.