Insight into low-temperature CH₄ combustion over CeO₂-Pd-MgAl₂O₄ catalysts by modulating metal-support interactions

The serial Pd/CeO₂/MgAl₂O₄, CeO₂/Pd/MgAl₂O₄, and Pd-CeO₂/MgAl₂O₄ catalysts were successfully prepared for CH₄ combustion, in which the deposition sequence of CeO₂ and Pd was well regulated. Among these catalysts, the Pd/CeO₂/MgAl₂O₄ showed the highest activity (T₉₀ = 474 °C) and a low activation energy (62.2 kJ·mol⁻¹) for catalytic CH₄ combustion. It revealed that the introduction of CeO₂ and the change in loading order had little effect on the catalyst particle size and specific surface area. The superior performance should be attributed to the excellent low-temperature redox capacity, abundant surface oxygen species and Pd²⁺ species, which was originated from the different preparation strategy and metal-support interaction between Pd species and CeO₂. Besides, the addition of CeO₂ significantly increased the content of moderate and strong acidic groups on the catalyst surface, which reduced the SO₂ adsorption capacity, leading to an improvement in the anti-SO₂ poisoning ability. This study provides a reference for the rational design and regulation of catalyst structures.