(688a) Spectroscopic Investigation of Pd Structures Formed over CeO2 and MnOx-CeO2 Supports
One of the existing challenges for Pd-deposited CeO2-based systems is the active sites responsible for CO oxidation at low temperatures. In this work, in-situ x-ray absorption fine structure (XAFS) experiments were performed over Ce and Mn solid solution catalysts to determine the change in the local structure of Pd during CO oxidation. Both Pd2+ ionic and PdO structural models were applied to fit the extended x-ray absorption fine structure (EXAFS). Additional characterization experiments through x-ray photoelectron spectroscopy (XPS), raman spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were conducted to explain Pd formation during CO oxidation. Our results indicated that both Pd2+ ionic structures and highly dispersed PdO nanoclusters were forming on CeO2 and MnOx-CeO2 supports. The close interaction of Pd2+ ionic structure and PdO phase possibly resulted in high activity for CO oxidation.