Effect of CeO 2 loading on the surface and catalytic behaviors of CeO 2-Al 2O 3-supported Pt catalysts

Abstract

Pt catalysts supported on mixed CeO 2-Al 2O 3 carriers with different CeO 2 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 CeO 2 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 CeO 2 (≤6 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 CeO 2 loading on the catalytic behavior of supported Pt catalysts in the reaction of CO 2 reforming of CH 4 was determined. Addition of cerium oxide results in improvement of catalytic performance for the reforming of methane with CO 2. Pt catalyst with 1 wt.% of CeO 2 exhibited the highest specific activity and stability, due to the increase in the metal–support interface area, caused by the higher Pt dispersion.