Long-term operation of a solid oxide fuel cell with MoNi-CeO2 as anode directly fed by biogas containing simultaneously sulphur and siloxane

This work analyses the long-term behaviour of MoNi-CeO2 (MoNi-Ce) anode in a direct internal reforming solid oxide fuel cell (DIR-SOFC) fed by biogas containing simultaneously sulphur and siloxanes. Both impurities are common in biogas and it is considered that they damage SOFC performance. An electrolyte supported cell with MoNi-Ce was operated under load demand (140 mA cm(-2)) at 750 degrees C in clean biogas for 116 h, followed by biogas with 10 ppm(v) H2S and 0.5 ppm(v) D4 siloxane (octamethylcyclotetrasiloxane) for 1737 h, and finally, clean biogas again for 96 h. Cell performance was periodically evaluated using electrochemical methods. Posttest analyses were conducted by SEM-EDS and XPS. The results show a stable cell performance in clean biogas, while the presence of both impurities in biogas initially led to a drop in performance, but without significant degradation after testing. A partial recovery in performance is observed after stopping both impurities in biogas. Silicon and small traces of carbon and sulphur were detected on the anode surface. It is demonstrated that MoNi-Ce exhibits high tolerance to the co-presence of H2S and D4 in biogas and good resistance to carbon deposition.

Automated summary

The study demonstrates that the MoNi-Ce anode exhibits high tolerance to the co-presence of H2S and D4 in biogas and good resistance to carbon deposition.