Preparation of fluorinated Cr2O3 hexagonal prism and catalytic performance for the dehydrofluorination of 1,1-difluoroethane to vinyl fluoride

Abstract A Cr 2 O 3 hexagonal prism structure synthesized via the reaction of aqueous CrCl 3 solution with NaBH 4 solution at room temperature followed by calcination of the precipitate in N 2 atmosphere at 500 °C is investigated as an efficient catalyst for dehydrofluorination of 1,1-difluoroethane producing vinyl fluoride. With the assistance of scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy, experimental results revealed that the uniform hexagonal prism has a prism length of 285 ± 43 nm and width of 233 ± 33 nm. It is in the form of loose and net-like aggregation of nano-Cr 2 O 3 with diameter less than 3–5 nm with polycrystalline structure. NH 3 temperature programmed desorption and chlorodifluoromethane dismutation experiments confirm the existence of relatively abundant and strong acidic sites. As a catalyst for dehydrofluorination of 1,1-difluoroethane, compared with commercial Cr 2 O 3 , much higher activity and stability were observed due to the evolution of CrO x F y species and much higher surface area and mesoporous structure. No significant morphology changes or sintering of the catalyst are observed after 70-h reaction. Compared with the commercial Cr 2 O 3 , we suggest that the much smaller size of Cr 2 O 3 crystalline which possesses higher surface energy, lower strength, and more abundant Lewis acidity and the formation of CrO x F y during reaction over hexagonal prism catalyst probably contributes to the activity and stability difference between these two catalysts. Graphical Abstract