An ultra-stable nanosized Ce0.9Fe0.1O2 solid solution with an excellent catalytic performance towards CH4 oxidation

Abstract

Activation of the C–H bonds in CH₄ is relatively difficult, since CH₄ is a quite a stable hydrocarbon with an extremely high ignition temperature (>1600 °C), which usually causes sintering and deactivation of catalysts. It remains a challenge to find catalysts that can show both good catalytic activity and thermal stability. In this work, Fe³⁺ doped CeO₂ nanoparticles were initially prepared and tested for catalytic activity towards CH₄ combustion. Systematic sample characterizations indicate that our nanoparticles were exposed by highly energetic facets (200), which yielded an excellent catalytic performance and thermal stability. The total conversion of CH₄ at a specific velocity of 60 000 ml g⁻¹ h⁻¹ appeared at T₁₀₀ = 520 °C, about 100 °C lower than that under similar test conditions previously reported for the best Ce–Fe–O solid solution catalysts. Strikingly, the present nanoparticles were also merited by an ultra-high thermal stability, since no particle growth or agglomeration is detected after high-temperature treatment, and since both the structure and oxygen species of the catalysts did not change at all before and after catalytic tests. The catalysts did not show any sign of deactivation, even when the test time was beyond 100 h. The surface oxygen species on the exposed (200) plane of the nanoparticles could be beneficial for the excellent catalytic performance towards CH₄ combustion.