Catalytic Total Oxidation of SOFC Exhaust Gas on Cu-Mn Catalysts

SOFC exhaust gases, such as methane and carbon monoxide, cause environmental problems. However, extra energy can be realized from oxidizing these out-gases into CO₂ and H₂O. This extra energy can be recycled in an SOFC system and increase the thermal efficiency. Thus the development of new catalysts that lower the oxidation temperature will make the SOFC system more efficient.

           CULLEN et. al.[1] reported high conversion rate of SOFC exhaust gas using a La-Cu-Mn impregnated alumina catalyst and a Pt-Pd catalyst in series. In this work, Cu-Mn catalysts that are used in the oxidation of methane or carbon monoxide were tested for SOFC exhaust gas oxidation.

           For determining the best ratio of Cu-Mn in catalysts, different ratios of La₂O₃-MnO-CuO/γ-Al₂O₃catalysts were prepared. The result shows approximtely 0.5 to 2 Cu/Mn ratio is the best composition for SOFC exhaust gas oxidation[Fig. 1].

Fig. 1. Conversion of CO(160℃), H₂(240℃), CH₄(460℃) with various Cu-Mn ratio.

           Cu-Mn perovskite and spinel supported catalysts were also tested. The perovskite supported catalysts showed much higher activity than the spinel supported. This was especially so for the case of methane conversion; the perovskite supported catalysts showed similar performance to alumina supported. The methane conversion of reference, CP and MP were 53.1%, 55.1% and 56.3% at 500℃, respectively.

References

[1] Greg CULLEN, Jon P. Wagner, Georg Anfang, Chandra Ratnasamy, METHOD FOR REMOVING CO, H₂ AND CH₄ FROM AN ANODE WASTE GAS OF A FUEL CELL AND CATALYST SYSTEM USEFUL FOR REMOVING THESE GASES, US 2012/0128563 Al, 2012