Phenylacetylene half-hydrogenation with Pd supported on vitreous materials having different chemical compositions

Pd metal has been supported on vitreous materials prepared by the gel route. Three supports with different chemical compositions of the SiO₂, Al₂O₃ and Na₂O systems were prepared; the corresponding catalysts, performed with very similar degrees of metal dispersion and Pd loading, have been used in the half-hydrogenation of phenylacetylene at different H₂ pressures. The results display an analogous behaviour with modest changes of the catalytic properties on changing the chemical composition of the support. The relatively better catalytic activity of the catalyst with smaller alkaline content is discussed in terms of the possible electronic shift from the metal to the support.