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 gamma-Al2O3. A model reaction of catalytic methane-combustion is employed here to evaluate the three Pd@CeO2/gamma-Al2O3 samples. As a result, the sample Pd@CeO2-S-850 prepared via supramolecular self-assembly and calcined at 850 degrees C exhibits superior catalytic performance to the others, which has a far lower light-off temperature (T-50 of about 364 degrees C). Moreover, almost no deterioration of Pd@CeO2-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@CeO2 samples toward catalytic methane combustion.