Experimental and DFT Mechanistic Study of Dehydrohalogenation of 1-Chloro-1,1-difluoroethane over Metal Fluorides

Vinylidene fluoride (VDF) is one of the major fluorinated monomers. Currently, it is produced via the pyrolysis of 1-chloro-1,1-difluoroethane at above 650 °C without any catalyst. Herein, we propose that metal fluorides are promising catalysts that selectively promote the pyrolysis at 300–450 °C. With various metal fluorides as the catalysts, the conversion rate increases with the amount of acidic sites, which is also reinforced by the Bader charges q. The affinity to Cl of the metal fluorides is responsible for the selectivity. However, the high affinity to Cl also leads to the chlorination of metal fluorides forming metal chlorides followed by the deactivation of the catalyst. Different from other metal fluorides, F defects play a major role in the performance of AlF3. With an increase in F defects, the selectivity changes from vinylidene chlorofluoride (dehydrofluorination) to VDF (dehydrochlorination), which further confirms the role of affinity to Cl in the selectivity.