Activating Edge Sites on Pd Catalysts for Selective Hydrogenation of Acetylene via Selective Ga2O3 Decoration

Pd catalysts are industrially used in the selective hydrogenation of acetylene to ethylene. Terrace Pd atoms of the closely packed {111} facets on supported Pd particles are generally considered to be the catalytically active sites. We herein report that deposition of an appropriate amount of Ga203 adlayers on Pd particles supported on alumina by the atomic layer deposition (ALD) technique substantially enhanced the catalytic activity, selectivity, and stability in the selective hydrogenation of acetylene to ethylene. Structural characterization results demonstrate that Ga203 is preferentially deposited at the edges and open facets of Pd particles with the ALD technique. This transforms the poisoning edge sites of the {111} facets into the catalytically active terrace -like sites, leading to an increase in the number of active sites and subsequently the enhancement of the catalytic activity; this also suppresses the formation of poisoning carbonaceous deposits on the open facets and blocks the migration of carbonaceous deposits from the open facets to the neighboring active {111} facets, leading to a significant improvement in catalytic stability. These results demonstrate a concept of selective oxide decoration to comprehensively improve the performance of supported metal catalysts and provide a practical strategy.