Palladium black as model catalyst in the hydrogenolysis of CCl2F2 (CFC-12) into CH2F2 (HFC-32)

Palladium black is applied as a model catalyst for the hydrogenolysis of CCl2F2 into CH2F2 over carbon supported palladium. The performance of palladium black is comparable with that of palladium on activated carbon. Fresh and used samples are characterized with X-ray diffraction (XRD), temperature programmed reduction (TPR), and temperature programmed oxidation (TPO) in a differential scanning calorimeter (DSC). Under reaction conditions, at temperatures as low as 423 K, palladium is converted into palladium carbide (PdC0.15). The amount of carbon on the catalytic surface is negligible. Fluorine present has no catalytic effect. Methane treatment (>523 K) and ethene treatment (>448 K) also lead to the formation of palladium carbide. In those cases carbon is deposited on the surface of the palladium. The amount of hydrogen in fresh palladium, determined by measuring the temperature of decomposition of palladium hydride at different partial pressures of hydrogen and by measuring the heat of decomposition in DSC, is as PdH0.6. This amount is in agreement with the value as obtained by TPR and as reported in literature.