In situ Raman spectroscopy studies on chromium oxide catalyst in an anhydrous hydrogen fluoride atmosphere

Changes of different chromium oxide species [Cr(VI), Cr(V) and Cr(III)] were investigated using in situ Raman spectroscopy in an anhydrous hydrogen fluoride (AHF) atmosphere. It was found that the Cr(VI) (CrO 3 ) and Cr(V) (YCrO 4 ) species were easy to fluorinate, and generated CrO 2 F 2 or/and CrOF 3 , while the Cr(III) (Cr 2 O 3 ) species was difficult to fluorinate. Moreover, the CrO 2 F 2 and CrOF 3 species were stable in the AHF atmosphere, but they easily transform into CrO 3 in N 2 atmosphere and further decomposed to Cr 2 O 3 at 400 °C. Moreover, Cl/F exchange reaction of CF 3 CH 2 Cl to CF 3 CH 2 F over these Cr species indicated that the high‐oxidation‐state CrO x F y (CrO 2 F 2 and CrOF 3 ) species exhibited much higher reactivities than Cr 2 O 3 , suggesting that these species (CrO 2 F 2 and CrOF 3 ) may be the active phases of the reaction. Copyright © 2010 John Wiley & Sons, Ltd.