Enhanced coking resistance of a Ni cermet anode by a chromates protective layer

Ni-based anodes of SOFCs are susceptible to coking, which greatly limits practical application of direct methane-based fuels. An indirect internal reformer is an effective way to convert methane-based fuels into syngas before they reach anode. In this work, catalytic activity of a redox-stable perovskite La0.7Sr0.3Cr0.8Fe0.2O3-delta (LSCrFO) for methane conversion was evaluated. The catalyst was fabricated as an anodic protective layer to improve coking resistance of a Ni cermet anode. Using wet CH4 as a fuel, the LSCrFO-modified cell showed excellent power output and good coking resistance with peak power density of 1.59W cm(-2) at 800 degrees C. The cell demonstrated good durability lasting for at least 100 h. While the bare cell without the protective layer showed poor durability with the cell voltage fast dropped from 0.75V to 0.4V within 30mM. Under wet coal bed methane (CBM) operation, obvious performance degradation within 35 h (1.7 mV h(-1)) was observed due to the influence of heavy carbon compounds in CBM. The pre- and post-mortem microstructures and carbon analysis of the anode surface and catalyst surface were further conducted. (C) 2018 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.