Preparation of bimetallic Pd-Fe/Al2O3 catalysts by underpotential deposition of iron

Bimetallic Pd-Fe/Al2O3 catalysts were prepared by underpotential deposition (UPD) of iron on parent Pd/Al2O3 catalysts of varying dispersion. The potential of palladium particles was controlled by the supplementary redox system H+/H-2. Iron introduced by this method improves the activity of small palladium particles for the hydrogenation of isoprene in the liquid phase. An explanation of this phenomenon would be a selective deposit of iron on or near the palladium sites of low coordination. However, the promoting effect of iron disappears after exposure of bimetallic catalysts to air and subsequent reduction.