Effect of nickel content and preparation method on the performance of Ni-Al₂O₃ towards the applications in solid oxide fuel cells

Ni-Al₂O₃ composites with varying contents of nickel are synthesized via a glycine nitrate process (GNP) and an impregnation process (IMP). Their potential application as an anode functional layer for internal methane CO₂ reforming in a solid oxide fuel cell is investigated. H₂-TPR results show that the chemical interaction between NiO and Al₂O₃ decreases as the nickel content increases. Catalytic tests demonstrate that 15 wt.% Ni-Al₂O₃ catalysts exhibit the best catalytic activity for methane CO₂ reforming. However, the carbon formation rates over Ni-Al₂O₃ prepared via GNP are lower than those over Ni-Al₂O₃ prepared via IMP using the same amounts of nickel, with the exception of the 1 wt.% Ni-Al₂O ₃ catalyst. Raman spectroscopy and O₂-TPO results indicate that the degree of graphitization and the amount of carbon deposited on the 15 wt.% Ni-Al₂O₃ catalyst synthesized via GNP are lower than those of the catalyst prepared via IMP following a 60 h stability test. A cell with a 15 wt.% Ni-Al₂O₃ catalyst layer prepared via GNP is fabricated that delivers a peak power density of 1006 mW cm^-2 at 850 °C when operating on methane-CO₂ gas mixtures, which is comparable to that observed when operating on hydrogen fuel.