Combustion-synthesized Ru-Al₂O₃ composites as anode catalyst layer of a solid oxide fuel cell operating on methane

Ru-Al₂O₃ composites with varied Ru contents were synthesized by a glycine-nitrate combustion technique. Their potential application as anode catalyst functional layer of a solid-oxide fuel cell operating on methane fuel was investigated. Catalytic tests demonstrated the 3-7 wt.% Ru-Al₂O₃ composites had high catalytic activity for methane partial oxidation and CO₂/H₂O reforming reactions, while 1 wt.% Ru-Al₂O₃ had insufficient activity. The 3 wt.% Ru-Al₂O₃ catalyst also showed excellent operation stability and good thermal-mechanical compatibility with Ni-YSZ anode. H ₂-TPR and TEM results indicated there was strong interaction between RuO_x and Al₂O₃ in the as-synthesized catalysts, which may account for the good catalytic stability of 3 wt.% Ru-Al ₂O₃ catalyst. O₂-TPO results demonstrated Ru-Al₂O₃ also had excellent coking resistance. Furthermore, the carbon deposited over Ru-Al₂O₃ had lower graphitization degree than that deposited over Ni-Al₂O₃, suggesting the easier elimination of potential carbon deposited over the Ru-Al₂O₃ catalysts. A cell with 3 wt.% Ru-Al ₂O₃ catalyst functional layer was prepared, wh-ich delivered peak power densities of 1006, 952 and 929 mW cm^-2 at 850 °C, operating on methane-O₂, methane-H₂O and methane-CO₂ gas mixtures, respectively, comparable to that operating on hydrogen fuel. It highly promised 3 wt.% Ru-Al₂O₃ as a coking resistant catalyst layer for solid-oxide fuel cells.