Competitive hydrogenation in alkene–alkyne–diene systems with palladium and platinum catalysts

Competitive hydrogenation of alkene, alkyne and diene substrates (C₆–C₈) over palladium and platinum catalysts were studied at 20°C and atmospheric pressure. Selectivities of these reactions were determined and the substrates relative adsorption coefficients calculated. It was found that hydrogenations of alkynic and dienic substrates were preferred in alkyne–alkene and diene–alkene systems, respectively. In these systems palladium catalyst selectivity was higher than selectivity of the platinum catalyst, due to higher relative adsorption coefficients of corresponding substrate couples on the palladium catalyst.