Abstract:
Adsorption of hydrogen and oxygen, titration of preadsorbed oxygen, benzene hydrogenation and cyclopcntane hydrogenolysis were performed on palladium catalysts of widely varying dispersion. A change in the stoichiometry of oxygen adsorption is found when increasing the metallic dispersion. On clean supports, free of sulphur and iron, the turn over number for both reactions of hydrocarbons is constant and independant of the dispersion of Pd. After a suitable reduction, sulphur may preferentially inhibit hydrogenolysis, while iron preferentially inhibits hydrogenation. On an industrial silica support the turn over for hydrogenolysis changes with dispersion ; this elTect is attributed to contamination of Pd by iron from the support.
