AuRu/meso-Mn₂O₃: A Highly Active and Stable Catalyst for Methane Combustion

Three-dimensionally ordered mesoporous Mn₂O₃ (meso-Mn₂O₃) and its supported Au, Ru, and AuRu alloy (0.49 wt% Au/meso-Mn₂O₃, 0.48 wt% Ru/meso-Mn₂O₃, and 0.97 wt% AuRu/meso-Mn₂O₃ (Au/Ru molar ratio = 0.98)) nanocatalysts were prepared using the KIT-6-templating and polyvinyl alcohol-protected reduction methods, respectively. Physicochemical properties of the samples were characterized by means of numerous techniques, and their catalytic activities were evaluated for the combustion of methane. It is found that among all of the samples, 0.48 wt% Ru/meso-Mn ₂O₃ and 0.97 wt% AuRu/meso-Mn₂O₃ performed the best (the reaction temperature (T_90%) at 90% methane conversion was 530-540°C), but the latter showed a better thermal stability than the former. The partial deactivation of 0.97 wt% AuRu/meso-Mn₂O₃ due to H₂O or CO₂ introduction was reversible. It is concluded that the good catalytic activity and thermal stability of 0.97 wt% AuRu/meso-Mn₂O₃ was associated with the high dispersion of AuRu alloy NPs (2-5 nm) on the surface of meso-Mn₂O₃ and good low-temperature reducibility. (paper)