Abstract:

A series of PdO-CeO2 composite catalysts were prepared using a co-precipitation method and tested for low temperature CO oxidation. The catalysts were further characterized by X-ray diffraction (XRD), the Brunauer-Emmett-Teller (BET) technique, chemisorption of CO, temperature programmed reduction (TPR), and a pulse reaction technique. Results of XRD indicated that CexPd1-xO2-δsolid solution was formed when the catalysts were calcined at 400-800 ℃, while PdOor metal Pd species re-migrated to the catalyst surface when it was calcined at a higher temperature (1000 ℃). The turnover frequency (TOF) for the CO oxidation reaction over these catalysts was found to be independent on the Pd particle size and it increased with increasing the content of CexPd1-xO2-δsolid solution in the catalyst. This suggests that the solid solution might be the active phase for the reaction. Furthermore, pulse reaction results indicated that oxidized Pd species were more active than metallic Pd.

Key words: PdO-CeO2, CO oxidation, CexPd1-xO2-δ solid solution