Toluene combustion on γ-Al 2O 3–CeO 2 catalysts prepared from boehmite and cerium nitrate

Abstract

γ-Al 2O 3–Ce catalysts were obtained by the impregnation of boehmite with cerium nitrate at different Ce contents (1, 5, 10, 20 wt%) and tested in the catalytic combustion of toluene. The catalysts annealed at 650 °C showed a diminution of the BET specific surface areas as a function of the cerium content. At low cerium content, the XRD spectra showed the γ-Al 2O 3 phase, whereas at high cerium content, the γ-Al 2O 3 phase and cerium oxide were observed. A diminution of the Lewis acidity was shown by the FTIR-pyridine absorption spectra. Both Ce 3+ and Ce 4+in variable proportions were observed by XPS. It has been found that the activity for the toluene combustion can be related to the C 4+/Ce 3+ ratio obtained in the various catalysts. The higher the C 4+/Ce 3+ ratio is the higher the toluene combustion activity.