Reforming activity and carbon deposition on cermet catalysts for fuel electrodes of solid oxide fuel cells

The activities of cermet catalysts composed of Ni and oxides for steam reforming of methane were investigated for internal reforming of solid oxide fuel cells. For all catalysts studied, the reaction attained almost equilibrium above 500 °C at the space velocity of 20,000 l kg−1 h−1. The kinetic-controlled reaction and difference in activity among the catalysts were observable at S.V. = 60,000 l kg−1 h−1. The reforming activity was higher for Ni–YSZ (YSZ: yttria-stabilized zirconia) than Ni–ScSZ (ScSZ: scandia-stabilized zirconia), whereas the highest activity was attained on Ni/Al2O3. However, the catalyst performance was degraded with carbon deposition in the course of the reaction. The tolerance to carbon deposition and, therefore, the life of the catalyst was significantly affected by the oxide material in the cermet. The carbon deposition was most rapid on Ni/Al2O3. The high loading of Ni also facilitated the deposition on the Ni–YSZ and Ni–ScSZ catalysts. It is noted that the carbon deposition rate was significantly smaller for Ni–ScSZ than the case of the Ni–YSZ.