Heterogeneous Palladium Catalysts in the Hydrogenation of the Carbon-carbon Double Bond

The results of studies over the past ten years in the field of C=C bond hydrogenation in the presence of palladium catalysts deposited on various inorganic and organic carriers such activated carbons, carbon nanotubes, alumina, zeolites, or composite materials based on Al₂O₃-SiO₂, polystyrene, polypropyleneimine, polyamidoamine and hybrid inorganic/ polymer-carriers, are presented. The selectivity and rates of the hydrogenation process are considered and some comparisons are made. Porous supports and containing dendrimers generally retain palladium particles more effectively. Nanosized palladium stabilized by different dendrimers catalyzes the hydrogenation of C=C bonds in polyfunctional compounds chemoselectively without affecting functional groups, such as CHO, C=O, C(O)OR, CN, NO2, and halogens.