In-situXAFS study for calcination process of Cr catalyst supported on γ-Al2O3and SiO2

The catalytic performance is largely affected by the oxidation state of supported Cr species, and its control changes the activity of Cr catalysts and the selectivity of products. In this study, the calcination process of the supported Cr catalysts on γ-Al 2 O 3 and SiO 2 was investigated by in-situ XAFS spectroscopy. The hydrate species was first supported by the impregnation method and was converted to CrO 3 via Cr 2 O 3 during the calcination process on both supporting materials. It was found that the temperature to complete the oxidation from Cr 2 O 3 to CrO 3 on SiO 2 was higher than that on γ-Al 2 O 3 . The similarity of the interatomic distance between the surface oxygen atoms of the intermediate Cr 2 O 3 species to that of SiO 2 contributes to the stabilization of Cr 2 O 3 on SiO 2 during the calcination process.