| Popis: |
Pd/CeO2 catalysts with different metallic Pd loading were synthesized by impregnation method. The physicochemical properties of prepared Pd/CeO2 catalysts and corresponding precursors were studied by XRD, XPS, H2-TPD and H2-TPR. Moreover, the catalytic performance of the Pd/CeO2 catalysts was investigated via gas phase benzene hydrogenation reaction at the temperature of 100–200 °C under atmosphere pressure. Results show that the catalytic performance of prepared Pd/CeO2 catalysts is directly related to the metallic Pd content. The amounts of active metallic Pd and adsorbed-desorbed hydrogen species on Pd/CeO2 catalysts increase with the increasing metallic Pd loading from 1.0 to 3.0%, while the numbers of them are slightly reduced on Pd/CeO2(3.5) catalyst. Furthermore, metallic Pd is highly dispersed on the nano-CeO2 supports, therefore, the prepared Pd/CeO2 catalysts present good gas phase benzene catalytic hydrogenation performance. At 200 °C, the benzene conversion over the Pd/CeO2 catalysts with different metallic Pd loading follows the rule: Pd/CeO2(3.0) > Pd/CeO2(3.5) > Pd/CeO2(2.5) > Pd/CeO2(2.0) > Pd/CeO2(1.5) > Pd/CeO2(1.0), corresponding values are 94.3, 96.4, 89.9, 82.8, 72.7, 42.6 and 94.3%. And the cyclohexane selectivity is 100% on all prepared Pd/CeO2 catalysts. |
