Toluene combustion on γ-Al2O3–CeO2 catalysts prepared from boehmite and cerium nitrate

γ-Al2O3–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-Al2O3 phase, whereas at high cerium content, the γ-Al2O3 phase and cerium oxide were observed. A diminution of the Lewis acidity was shown by the FTIR-pyridine absorption spectra. Both Ce3+ and Ce4+in variable proportions were observed by XPS. It has been found that the activity for the toluene combustion can be related to the C4+/Ce3+ ratio obtained in the various catalysts. The higher the C4+/Ce3+ ratio is the higher the toluene combustion activity.

The catalytic activity of Al2O3–Ce catalysts toward the total oxidation of toluene was plotted a “S-Shape” light-off curve. The effect of Ce content (1, 5, 10 and 20 wt% Ce) in the toluene combustion is evident since the displacement to lower temperature for the total combustion of toluene is of 89 °C for the Ce (20%) support in comparing with the alumina reference catalyst.Figure optionsDownload as PowerPoint slide