Electron microscopy study on the Pd-Ce interaction in CeOx-Pd/α-Al2O3 catalysts for methane dry reforming

M.S. MORENO; F. WANG; M. MALAC; T. KASAMA; C.E. GIGOLA; I. COSTILLA ; M.D. SÁNCHEZ

JOURNAL OF APPLIED PHYSICS

AMER INST PHYSICS

Año: 2009 vol. 105 p. 83531 - 83536

0021-8979

We have investigated the interaction between Pd and Ce in a (0.47wt %) CeOx?Pd (1wt%)/a-Al2O3 catalyst that is used in the reforming reaction of CH4 with CO2. The freshly reduced catalyst was characterized by various electron microscopy techniques, such as elemental mapping, Z-contrast imaging, and electron energy-loss spectroscopy to understand the role of Ce on a microscopic scale. The high spatial resolution elemental mapping indicates that CeOx is located in close proximity of the palladium nanoparticles. High-resolution lattice images and energy-loss spectra obtained in the vicinity of the Pd particles show an anisotropic distribution of CeOx crystallites limited to the interface region between Pd and the substrate but not covering the surface of the Pd nanoparticles. Energy-loss near edge fine structure of Pd M edges reveals that the Pd nanoparticles are not oxidized.