(544gu) Improving Gasoline-Fed Solid Oxide Fuel Cell Performance with Nickel Catalyst Anode

Solid oxide fuel cells (SOFCs) are a promising energy conversion device because they can efficiently and directly convert the chemical energy of fuels into electrical energy. Due to the high operating temperatures (typically 600–1000 °C), SOFCs hold particular promise because of their ability to use a variety of complex liquid fuels, such as conventional liquid transportation fuels (e.g., gasoline, diesel-like fuels and jet fuels) and next generation liquid bio-fuels (e.g., biodiesel), either by using external reforming systems or directly feeding these fuels to their inexpensive transition metal-based anodes. Nickel-based anodes are commonly used in SOFCs due to their low cost, good chemical stability, and excellent catalytic activity toward hydrogen oxidation and reforming of small hydrocarbon molecules. However, the Ni-based anodes are well known for promoting severe surface carbon deposition. Excessive formation of carbon species on the anode leads to a rapid deterioration of the cell performance by physically blocking access of the reactants to the active catalyst sites. We report a Ni-Mo bimetallic catalyst supported on ceria-zirconia (CZ) prepared using co-impregnation as an efficient catalyst for partial oxidation of isooctane at high space velocities. It is also used as a catalytic micro-reforming layer on a conventional Ni/YSZ-based SOFC to form a bi-layer anode. The catalysts were characterized using a number of analytical techniques and catalyst performance for partial oxidation of isooctane was investigated at 750 °C; atmospheric pressure; air and fuel flow rates of 100 sccm and 3 ml/h, respectively; and O₂/C ratio of 0.4. The addition of Mo increases the catalytic activity in terms of isooctane conversion and syngas yields. Most significantly, the presence of Mo enhances the long-term stability of the Ni-based catalyst. We have further demonstrated that the carbon tolerance of Ni can be significantly improved by Mo addition. When applied it as a reforming layer in a SOFC running on isooctane, the cell showed a very slow degradation rate of 4.8 mV h^−1 during 12 h of operation at 750 °C. The excellent catalytic activity and stability suggest that Ni-Mo/CZ is an excellent material for a bi-layer anode of SOFC with superior coke tolerance.