Effect of CeO2 loading on the surface and catalytic behaviors of CeO2-Al2O3-supported Pt catalysts

Pt catalysts supported on mixed CeO2-Al2O3 carriers with different CeO2 loading (0.5-10.3 wt.%) were prepared by wetness impregnation method. The catalysts were characterized by S-BET, X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR) and thermogravimetric analysis (TG). It was shown that pretreatment temperature and the concentration Of CeO2 in the support influences significantly on the morphology of Pt. XRD showed the formation of nanocrystallites of Pt on the surface of alumina and low-loaded CeO2 (less than or equal to6 wt.%) samples at higher temperature of calcination (1073 K). Amorphous Pt was observed in all reduced samples. XPS spectra showed the presence of interaction between Pt and Ce, which leads to easy surface reduction of both, ceria and platinum, as revealed by TPR patterns. The effect Of CeO2 loading on the catalytic behavior of supported Pt catalysts in the reaction Of CO2 reforming of CH4 was determined. Addition of cerium oxide results in improvement of catalytic performance for the reforming of methane with CO2. Pt catalyst with I wt-% Of CeO2 exhibited the highest specific activity and stability, due to the increase in the metal-support interface area, caused by the higher Pt dispersion. (C) 2003 Elsevier B.V. All rights reserved.