Fluorination of dichlorodifluoromethane to synthesize tetrafluoromethane over Cr2O3–AlF3 catalyst

A series of Cr2O3–AlF3 catalysts with different Cr2O3 contents were prepared by a deposition–precipitation method for the fluorination of dichlorodifluoromethane (CCl2F2) to synthesize tetrafluoromethane (CF4). The highest activity was obtained on the Cr2O3–AlF3 catalyst containing 61.2 wt.% of Cr2O3, with the CF4 yield of 94% at 400 °C. X-ray diffraction (XRD) and Raman spectroscopy results indicated the presence of bulk Cr2O3 and α-AlF3 phases in the catalysts. Ammonia temperature programmed desorption (NH3-TPD) and Fourier transformation infrared spectroscopy (FTIR) of pyridine chemisorption revealed strong Lewis acidity of the catalysts. The Cr species and Lewis acid in the Cr2O3–AlF3 catalysts were the active sites of fluorination and dismutation reaction of CCl2F2, respectively. This indicated bi-function catalytic performance of Cr2O3–AlF3 catalysts for fluorination and dismutation reaction.