Partial hydrogenation of 1,3-cyclooctadiene catalyzed by palladium-complex catalysts immobilized on silica

Silica-immobilized Pd-complex catalyst was prepared and applied to the hydrogenation of 1,3-cyclooctadiene (1,3-COD). The characterization of catalyst was conducted by EA, ICP-AES, TG, differential TG and XPS analyses. The result revealed that Pd-complexes were successfully immobilized on the silica support. The resulting catalyst was found to be more active and selective than the commercial Pd/C catalyst and the unsupported Pd-complex catalysts for the partial hydrogenation of 1,3-COD to cyclootene (COE). The introduction of N,N,N′,N′-tetramethylethylenediamine (tmeda) ligand to Pd-complex gave rise to a considerable increase of 1,3-COD conversion with the COE selectivity of higher than 99 mol%. Such an excellent catalytic performance can be attributed to electronic and geometric effects caused by the interaction between tmeda ligand and Pd atoms in the silica-immobilized Pd-complex catalyst.