Abstract: A high specific surface area Cr₂O₃-α-AlF₃ catalyst was prepared using a carbon hard template method. The synthesis procedure consisted of three consecutive steps: (1) the impregnation of a sucrose (C₁₂H₂₂O₁₁) aqueous solution with Cr₂O₃-γ-Al₂O₃ and subsequent thermal treatment; (2) the thermal treatment of the obtained solid with HF, C@Cr₂O₃-γ-Al₂O₃ can be completely transformed into C@Cr₂O₃-γ-AlF₃ at 400°C with hydrogen fluoride; (3) the removal of the carbon template in C@Cr₂O₃-γ- AlF₃ upon high temperature combustion giving the high surface area Cr₂O₃-γ-AlF₃ (115 m²·g^-1). The catalysts were characterized by X-ray diffraction (XRD), N₂ physisorption, ammonia temperatureprogrammed desorption (NH₃-TPD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersion X-ray (EDX) techniques. We found that the fluorination process was crucial for the resulting Cr₂O₃-α-AlF₃ with a high specific surface area of 115 m²·g^-1 under optimal conditions. The Cr₂O₃-α-AlF₃ catalyst with a high specific surface area was more active for the decomposition of 1,1-difluoroethane than the catalyst prepared by the direct fluorination of Cr₂O₃-γ-Al₂O₃, because it contained a higher amount of acid sites.

Key words: Cr₂O₃-&, alpha, -AlF₃, High specific surface area, Lewis acid, CH₃CHF₂ decomposition, X-ray diffraction