Kinetic and mass transfer in the hydrogenation of polyunsaturated organic compounds in the presence of supported Pd catalysts

The hydrogenation of 1,5-cyclo-octadiene has been studied on well-defined P d catalysts. The reaction is affected by internal diffusion of hydrogen int o the catalyst particles. Despite this limitation, the reaction orders of t he reactants have been determined. All the performed kinetic runs have been simulated and the kinetic and mass-transfer parameters giving the best fit of experimental data have been evaluated. The reaction occurs in two steps , in the first, a conjugate diene (1,3-cyclo-octene) is formed via isomeriz ation, then, hydrogenation occurs quickly forming the monoene. The hydrogen ation of the obtained cyclo-octene is relatively slow and strongly inhibite d by the presence of the cyclo-octadiene. This last reaction has, therefore , been used for comparing the activities of different palladium catalysts s howing an exponential behaviour of the reaction rate with the metal dispers ion. (C) 2001 Elsevier Science B.V. All rights reserved.