Catalytic combustion of methane is an effective solution to reducing the greenhouse gas emission from natural gas-fueled engines. However, existing methane combustion catalysts suffer from insufficient low-temperature activity and poor hydrothermal stability. In this study, we demonstrate that PdO nanoparticles supported on oxygen vacancy-rich NiAl₂O₄ spinel, prepared by a simple and affordable procedure, render a remarkable enhancement in catalytic methane combustion below 400 °C. The calcination temperature was used as a robust means to tune the concentration of oxygen vacancies in the NiAl₂O₄ spinel. The particle size of PdO can be effectively controlled by adjusting the temperature of the subsequent calcination of the Pd-loaded spinel catalyst. The optimized catalyst, Pd/NiAl₂O₄-900–550, i.e. NiAl₂O₄ calcined at 900 °C, impregnated with Pd, and subsequently calcined at 550 °C, achieved a T₅₀ as low as 325 °C, whilst exhibiting excellent stability. After continuous treatment in 10% H₂O at 750 °C for 10 h, T₅₀ remains at below 396 °C. The characterization of the catalyst before, after and in situ methane combustion confirms that the high oxygen vacancy concentration and stable PdO nanoparticles both contribute to its excellent activity and stability. The present study introduces a new paradigm for preparing cost-effective and scalable redox catalysts supported on NiAl₂O₄ spinel with rich and tunable oxygen vacancies.

中文翻译：

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与富含氧空位的 NiAl2O4 负载的 Pd 相比，甲烷的催化燃烧效果更好


甲烷催化燃烧是减少天然气发动机温室气体排放的有效解决方案。然而，现有的甲烷燃烧催化剂存在低温活性不足和水热稳定性差的问题。在这项研究中，我们证明了通过简单且经济的程序制备的负载在富含氧空位的NiAl ₂ O ₄尖晶石上的PdO纳米粒子，可以显着增强400°C以下的催化甲烷燃烧。煅烧温度被用作调节NiAl ₂ O ₄尖晶石中氧空位浓度的稳健手段。通过调节负载Pd尖晶石催化剂的后续煅烧温度可以有效控制PdO的粒径。优化的催化剂 Pd/NiAl ₂ O ₄ -900–550，即NiAl ₂ O ₄在 900 °C 下煅烧，用 Pd 浸渍，然后在 550 °C 下煅烧，实现了低至 325 °C 的T ₅₀ ，同时表现出优异的稳定性。在750℃下在10%H ₂ O中连续处理10小时后， T ₅₀保持在396℃以下。甲烷燃烧前后和原位催化剂的表征证实，高氧空位浓度和稳定的PdO纳米粒子都有助于其优异的活性和稳定性。 本研究引入了一种新的范例，用于制备具有丰富且可调节的氧空位的 NiAl ₂ O ₄尖晶石负载的经济有效且可扩展的氧化还原催化剂。