Development of a palladium on activated carbon for a conceptual process inthe selective hydrogenolysis of CCl2F2 (CFC-12) into CH2F2 (HFC-32)

The hydrogenolysis of CCl2F2 over 1 wt.% palladium, platinum, rhodium, ruth enium, iridium, and rhenium on activated carbon has been studied in a micro -flow reactor, in a temperature range of 450-540 K, H-2/CCl2F2 feed ratios between 1.5 and 20, a pressure up to 0.4 MPa, and a WHSV between 0.5 and 2 g/(g h). The main products of the reaction for all investigated catalysts w ere CHClF2, CH2F2, and methane. Palladium on activated carbon shows the hig hest selectivity to CH2F2 (70-90%) at all conversion levels. The activity, selectivity to CH2F2 and stability of the palladium catalyst is a strong fu nction of the hydrogen to CFC ratio, methane recycle ratio and the recycle of CHClF2 is not recommended. The catalyst proves to be stable over a perio d of 2000 h with simulated recycle streams and an optimum temperature for t he catalyst performance was found at 510 K. On the basis of the experimenta l data and a kinetic network a conceptual process design was made. In this design no hurdles have been encountered and this waste technology looks in economic prospective very promising. (C)2000 Elsevier Science B.V. All righ ts reserved.