Self-Assembled Pd@CeO 2 /γ-Al 2 O 3 Catalysts with Enhanced Activity for Catalytic Methane Combustion.

Pd@CeO ₂ /Al ₂ O ₃ catalysts are of great importance for real applications, such as three-way catalysis, CO oxidation, and methane combustion. In this article, the Pd@CeO ₂ 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@CeO ₂ nanospheres on γ-Al ₂ O ₃ . A model reaction of catalytic methane-combustion is employed here to evaluate the three Pd@CeO ₂ /γ-Al ₂ O ₃ samples. As a result, the sample Pd@CeO ₂ -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 (T ₅₀ of about 364 °C). Moreover, almost no deterioration of Pd@CeO ₂ -S-850 is observed after five sequent catalytic cycles. The analysis of H ₂ -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@CeO ₂ samples toward catalytic methane combustion.
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