Structure and Reactivity Studies of Cr_2O_3/Al_2O_3: The ODH of LPG

摘要

The nature of the surface chromium oxide species supported on Al_2O_3 for different chromium oxide contents was investigated by XRD, Raman spectroscopy and TPR experiments. The ambient Raman spectra for the samples suggest that tetrahedral chromates are present. The Raman spectra and XRD patterns reveal the presence of Cr_2O_3 crystals for the loadings above 15%. The TPR experiments reveal that essentially a single T_(max) temperature is observed for all Cr_2O_3/Al_2O_3 samples. Furthermore, the hydrogen per chromium consumption (H/Cr) decreases with an increase in chromium oxide loading. The effect of precursor used for the preparation of Cr_2O_3/Al_2O_3 catalysts was also studied and no significant difference in the structure and reduction properties of the surface chromium oxide species was observed. Catalytic studies of the Cr_2O_3/Al_2O_3 catalysts were also performed. These studies reveal that the surface chromium oxide species are the active sites for the ODH reaction.