Palladium hydrotalcites as precursors for the catalytic hydroconversion of CCl_2F_2 (CFC-12) and CHClF_2 (HCFC-22)

摘要

The synthesis of palladium hydrotalcite-like materials and their catalytic properties for the hydroconversion of CCl_2F_2 (CFC-12) and CHClF_2 (HCFC-22) are reported. These materials appear to be interesting catalysts for selective hydrodechlo- rination reactions. The influence of process parameters, such as reaction temperature and H_2/CFC-HCFC ratio on the hy- drogenolysis of CFC-12 and HCFC-22, has been investigated. In the reaction of CCl_2F_2, the main products were CH_2F_2, C~ and CHCIF_2. In the reaction of CHClF_2, the main products were CH_2F_2, CHF_3 and C~. The highest conversion and selectivity to CH_2F_2 are obtained on the heavily loaded Pd catalyst. A high H2/CFC-HCFC ratio favors the obtention of CH_2F_2. During the reaction, the formation of fluoride and Pd-carbide phases were detected.