Trimetallic platinum catalysts

The activity results clearly indicate that both Sn and Re significantly improves the activity of platinum in the hydrogenolysis of AcOBu. As seen in Figure 4 the specific activity (rSn+Re, mol/molpr0moterxh) of trimetallic catalysts has a maximum in the function of promoter concentration (Sn+Re) at 70 mmol/goataiyst (0.75 wt. % Re). 

A large screening was recently done to identify such a third metal, X, to add to platinum and ruthenium [52]. Figure 5 summarizes the behavior of the nine investigated Pt-Ru-X trimetallic electrocatalysts toward methanol oxidation. At low potentials, the Pt-Ru-Mo ternary catalyst gives the highest current densities compared to other ternary electrocatalysts. This catalyst exhibits a current density 10 times greater than Pt-Ru at a potential of 400 mV versus RHF under steady-state conditions (data taken after 5 minutes). 

Bimetallic (Pt-Bi) or trimetallic (Pt-Pd-Bi) catalysts are available commercially from Degussa [85]. Metal promoters such as bismuth or lead, were added to platinum metals by co-impregnation, by impregnation of the supported noble metal catalyst with an aqueous promoter salt solution, or by redox surface reaction. A very simple and efficient way of loading Pt/C or Pd/C catalysts with bismuth is to add the required amount of aqueous Bi0N03 solution to a suspension... 

By far the most widely explored approach to decrease the anodic potential has been the formation of bimetallic, trimetallic or multimetallic platinum based catalysts. In a bimetallic platinum based catalyst the second metal will be chosen... 

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