The dissociation of reactants and weak binding of intermediates are two key, but not easily fulfilled, criteria for high activity and selectivity in heterogeneous catalysis. Through a combination of scanning tunnelling microscopy and temperature programmed reaction measurements we describe here how individual, isolated atoms can change drastically the hydrogenation activity of a relatively inert metal surfaces. Single Pd atoms dispersed on Cu(111) can facilitate the adsorption of atomic hydrogen on Cu by lowering the activation barrier to dissociation. This facile hydrogen dissociation at Pd atom sites and the weak binding of hydrogen on Cu allows for very selective hydrogenation of key alkenes as compared Cu or Pd metal alone.  From the practical application standpoint, the very small amounts of precious metal required to produce single atom alloys catalysts makes them a very attractive alternative to traditional bimetallic catalysts.

Isolated metal atom geometries: A strategy for selective  heterogeneous hydrogenations

243rd National Meeting (2012)

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