ABSTRACT
Catalytic hydrogenation is a key reaction in organic chemistry. Therefore, both theoretical studies of the reaction stages and technological investigations are very important areas of research. The basic concepts of catalyst selection have been defined and also numerous problems of hydrogenation in solutions have been solved. This applies in equal measure to both homogeneous catalysis by metal complexes and heterogeneous catalysis by group VIII transition metal ions. Heterogenization of homogeneous catalysts provides additional possibilities for varying catalytic activity and for selectivity regulation. A comparison of olefin adsorption with their rates of hydrogenation has revealed that both enthalpy and entropy of coordinated ethylene molecules correlate with changes in polymer chain mobilities. While avoiding detailed comparison of immobilized catalysts with others, the readers shall only note that sometimes the parallels reveal kinetic features that are intrinsic in homogeneous hydrogenation catalysts, and at times resemble heterogeneous catalysts.