Characterization and Reactivity of Pd/MgO and Pd/γ-Al2O3 Catalysts in the Selective Hydrogenolysis of CCl2F2†

Al 2 O 3 and MgO supported Pd catalysts with 6 wt % loading are prepared by the wet impregnation method. The catalysts are made into two parts; one of them is dried at 110 °C, and the other one is calcined at 500 °C. Conversion of CCl 2 F 2 in hydrogen is carried out under identical reaction conditions on both dried and calcined catalysts after the catalysts are prereduced in H 2 at 400 °C for 3h. The fresh and the used catalysts are characterized by BET-surface area, X-ray diffraction (XRD), temperature programmed reduction (TPR), temperature programmed desorption (TPD) of NH 3, and X-ray photoelectron spectroscopy (XPS). XPS data shows that surface Pd species are more in MgO supported catalyst than in Al 2 O 3 supported one. In used catalysts, surface F - concentration is more on MgO than on Al 2 O 3 supported Pd catalyst. The MgO supported Pd catalyst (dried) showed higher reactivity and CH 2 F 2 selectivity compared to other catalysts. MgO support is found to be superior to Al 2 O 3 support for Pd for the reaction.