Effect of ZrO2 on the Structure of NiO/CeO2/||/EM>-Al2O3 Composite Catalysts

Using Ni(NO3)2 ¤6H2O, Al(NO3)3 ¤9H2O￡ ZrOCl2 ¤8H2O and Ce(NO3)3 ¤6H2O as raw materials, NiO/CeO2/Al2O3 and NiO/CeO2-ZrO2/A2O3 composite catalysts were prepared by co-precipitation method. Structures of the composite catalysts were investigated by X-ray diffraction (XRD), high resolution transmission electron microscope (TEM) and X-ray absorption near edge structure (XANES) spectroscope. Results indicate that NiO phase in NiO/CeO2/||/EM>-Al2O3 catalysts disappears above 600 ecause it interact with a ||/EM>-Al2O3 to form NiAl2O4 spinel. However, no NiAl2O4 spinel is found in NiO/CeO2-ZrO2/Al2O3 catalysts annealed at 700 ue to the formation of Zr0.30Ce0.45Al0.25O1.87aa solid solution.