Study of catalytic hydrogenation performance for the Pd/CeO 2 catalysts

Pd/CeO 2 catalysts with different metallic Pd loading were synthesized by impregnation method. The physicochemical properties of prepared Pd/CeO 2 catalysts and corresponding precursors were studied by XRD, XPS, H 2 -TPD and H 2 -TPR. Moreover, the catalytic performance of the Pd/CeO 2 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/CeO 2 catalysts is directly related to the metallic Pd content. The amounts of active metallic Pd and adsorbed-desorbed hydrogen species on Pd/CeO 2 catalysts increase with the increasing metallic Pd loading from 1.0 to 3.0%, while the numbers of them are slightly reduced on Pd/CeO 2 (3.5) catalyst. Furthermore, metallic Pd is highly dispersed on the nano-CeO 2 supports, therefore, the prepared Pd/CeO 2 catalysts present good gas phase benzene catalytic hydrogenation performance. At 200 °C, the benzene conversion over the Pd/CeO 2 catalysts with different metallic Pd loading follows the rule: Pd/CeO 2 (3.0) > Pd/CeO 2 (3.5) > Pd/CeO 2 (2.5) > Pd/CeO 2 (2.0) > Pd/CeO 2 (1.5) > Pd/CeO 2 (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/CeO 2 catalysts.