Liquid-phase heterogeneous hydrogenation of dicyclopentadiene

Liquid-phase hydrogenation of dicyclopentadiene (endo-tricyclo[5.2.1.02,6]deca-3,8-diene) in the presence of Pd/γ-Al2O3 catalyst (PC-25) in heptane at 76 °C proceeds consecutively via the intermediate endo-tricyclo[5.2.1.02,6]dec-3-ene with the final formation of endo-tricyclo[5.2.1.02,6]decane. No destruction of the norbornane skeleton occurred under the experimental conditions. Reaction products were identified, main reaction routes were determined, material balance was studied. Kinetic data indicate a clear separation of the process steps and a quantitative hydrogenation of the norbornene bond in the substrate at the first step with practically 100% selectivity and conversion. The first step was found to have the zero kinetic order in the starting diene, the second step has the first order in monoene. The similarity of adsorption characteristics of norbornenes of different structures was kinetically confirmed. A consecutive scheme was proposed for the mechanism of the process based on the combination of experimental data.