Hydrogenation of endo-endo dimer of Norbornadiene over Pd catalysts

The hydrogenation of endo-endo dimer of Norbornadiene using Pd/Al₂O₃ catalysts have been studied in a batchwise slurry reactor. The egg-shell catalyst was much more active than the uniform one. This can be attributed to the incomplete utilization of active sites near the center of the catalyst sample with uniform metal distribution resulting from diffusional hindrance. The kinetic studies of the egg-shell catalyst showed that the reaction rate is zeroth order with respect to norbornadiene and first order to partial pressure of hydrogen. The rate equation can be expressed as - r(NN) = 2.525 X 10² X exp (-4380/T)·P(H)(2) (mol/sec. g catal.). The reaction follows the Horiuti-Polanyi mechanism. Hydrogen is dissociatively adsorbed on metal; NN is strongly adsorbed on metal and the rate-limiting step is surface reaction.