Enhanced methane combustion performance and stability of the supported Pd nanoparticles by constructing the ordered mesoporous Co3O4-CeO2 interfaces.

The development of CH4 low-temperature combustion catalysts with high efficiency and good stability faces a major challenge. In this work, the supported noble metal catalysts with ordered mesoporous Co3O4-CeO2 interfaces and highly dispersed Pd2+ active sites were prepared by the KIT-6-templating and NaBH4 reduction methods. It was found that compared to 1.39 wt.% Pd/meso‑Co3O4 (1.39Pd/meso‑Co3O4) and 1.26 wt.% Pd/meso‑CeO2 (1.26Pd/meso‑CeO2), 1.43 wt.% Pd/meso‑Co2Ce1 (1.43Pd/meso‑Co2Ce1; n(Co3O4)/n(CeO2) molar ratio = 2 : 1) exhibited better catalytic activity for methane combustion (T50% = 328 °C and T90% = 378 °C at space velocity = 20,000 mL/(g·h); specific reaction rate at 280 °C = 0.42 μmol/(gcat·s) or 29.4 μmol/(gPd·s); and turnover frequency (TOFPd) at 280 °C = 6.33 × 10-3 s-1). Furthermore, the 1.43Pd/meso‑Co2Ce1 sample showed good catalytic stability. The presence of the Co3O4-CeO2 ordered mesoporous interfaces in 1.43Pd/meso‑Co2Ce1 promoted the generation of active oxygen species and effectively stabilized PdO active site, thereby enhancing catalytic activity of 1.43Pd/meso‑Co2Ce1 for CH4 combustion. In addition, methane combustion pathways over 1.43Pd/meso‑Co2Ce1 might be as follows: gas-phase methane → adsorbed methane → formate or carbonate → carbon dioxide and water. This work provides novel insights into the role of redox binary metal oxide interfaces in methane combustion.