Synthesis, characterization and performance of Pd-based core-shell methane oxidation nano-catalysts

In this paper, a comparative investigation of the catalytic performances of Pd@TiO2 and Pd@CeO2, core-shells nanocatalysts supported over functionalized alumina, for application to methane oxidation is presented. The results indicated that the Pd@CeO2/SiO2.Al2O3 core-shell nanocatalyst exhibited higher activity and stability than the Pd@TiO2/SiO2.Al2O3 nanocatalyst. Complete combustion of methane over the Pd@CeO2/SiO2.Al2O3 nanocatalyst was achieved at about 400 °C. By contrast, the maximum combustion of methane over the Pd@TiO2/SiO2.Al2O3 nanocatalyst was only attained at ∼550 °C. The Pd@TiO2/SiO2.Al2O3 nanocatalyst experienced deactivation, and a transient dip in methane conversion in the temperature region between 580 °C and 750 °C was also observed. The exceptional activity of the Pd@CeO2/SiO2.Al2O3 nanocatalyst was attributed to the intimate interaction between palladium (Pd) and ceria (CeO2) and efficient oxygen back-spillover at Pd and CeO2 interface resulting from the core-shell structure.