SYNTHESIS OF HFC-134A BY ISOMERIZATION AND HYDROGENATION

For the preparation of HFC-134a, the isomerization of CFC-114 and the hydrogenation of CFC-114a were investigated. Both reactions were catal yzed by AlCl3 and supported Pd catalysts, respectively. For the compar ison purpose, the isomerization of CFC-113 was carried out also. With virgin AlCl3 catalyst, both isomerization reactions proceeded after a certain induction period probably because the catalyst needed the acti vation by the halogen exchange. The catalyst deactivated gradually wit h the time on stream. However, the deactivation rate could be reduced by removing impurities from the reactants. Isomerization rate of CFC-1 14 was much slower than that of CFC-113. Palladium supported on carbon catalyzed the hydrogenation reaction quite selectively while the sele ctivity declined when the support was replaced with different supports . The catalytic activity and selectivity to desired products increased in the following order. Pd/kieselguhr<Pd/silica-alumina congruent to Pd/silica gel<Pd/TiO2<Pd/Al2O3<Pd/C