Self-Assembled Pd@CeO₂/γ-Al₂O₃ Catalysts with Enhanced Activity for Catalytic Methane Combustion

Pd@CeO₂/Al₂O₃ catalysts are of great importance for real applications, such as three-way catalysis, CO oxidation, and methane combustion. In this article, the Pd@CeO₂ core@shell nanospheres are prepared via the autoredox reaction in aqueous phase. Three kinds of methods are then employed, that is, electrostatic interaction, supramolecular self-assembly, and physical mixing, to support the as-prepared Pd@CeO₂ nanospheres on γ-Al₂O₃. A model reaction of catalytic methane-combustion is employed here to evaluate the three Pd@CeO₂/γ-Al₂O₃ samples. As a result, the sample Pd@CeO₂-S-850 prepared via supramolecular self-assembly and calcined at 850 °C exhibits superior catalytic performance to the others, which has a far lower light-off temperature (T₅₀ of about 364 °C). Moreover, almost no deterioration of Pd@CeO₂-S-850 is observed after five sequent catalytic cycles. The analysis of H₂-TPR curves concludes that there exists hydrogen spillover related to the strong metal–support interaction between Pd species and oxides. The strong metal–support interaction and the specific surface areas might be responsible for the catalytic performance of the Pd@CeO₂ samples toward catalytic methane combustion.