Selective hydrogenation of acetylene on Cu-Pd intermetallic compounds and Pd atoms substituted Cu(111) surfaces

The selective hydrogenation of acetylene was studied on the ordered Cu-Pd intermetallic compounds (L1(0)-type CuPd, L1(2)-type Cu3Pd, and L1(2)-type CuPd3) and Pd-modified Cu(111) surfaces through first-principles calculations. The catalytic selectivity and activity of Cu-Pd alloy catalysts are closely related to the crystal structure and composition of Cu-Pd intermetallic compounds and the size of Pd ensembles of Cu-based dilute alloy surface for the selective hydrogenation of acetylene to ethylene. Significantly, we found that the ordered Cu-Pd alloy surface containing isolated Pd atoms (i.e., L1(2)-type Cu3Pd(111) surface) is highly efficient for the selective hydrogenation reaction of C2H2 + H-2 -> C2H4. The contiguous Pd atom ensembles (Pd dimer and trimer) are catalytically active towards C2H2 + H -> C2H3 and C2H3 + H -> C2H4 reactions than the single Pd atom on a Pd-decorated Cu(111) surface. However, the small Pd ensembles on Cu(111) present a low chemical activity for H-2 dissociation compared with the ordered Cu-Pd intermetallic compounds. Our theoretical results provide a strategy of crystal phase and composition control for enhancing the selectivity and activity of Cu-Pd catalysts towards acetylene selective hydrogenation.

Automated summary

The study indicates that ordered Cu-Pd alloy surfaces containing isolated Pd atoms are highly efficient for the selective hydrogenation of acetylene, while adjacent Pd atom ensembles show strong catalytic activity towards other reactions.