Cost-effective promoter-doped Cu-based bimetallic catalysts for the selective hydrogenation of C2H2 to C2H4: the effect of the promoter on selectivity and activity

In order to probe into the effect of the promoter on the selectivity and activity towards C2H4 formation in the selective hydrogenation of C2H2 over cost-effective Cu-based bimetallic catalysts, different metal promoter M-modified Cu catalysts including Ni, Ag, Au, Pt, Pd and Rh have been employed to fully investigate the selective hydrogenation of C2H2 using density functional theory calculations together with microkinetic modeling. The results show that the adsorption ability of C2H2 is far stronger than that of C2H4 on different Cu-based catalysts, which favors the activation and hydrogenation of C2H2. The type of promoter obviously affects the preferable pathway of C2H2 selective hydrogenation, and ultimately alters the selectivity of the products; only on PdCu(211) and AgCu(211) surfaces, the C2H4 desorption pathway is the most favorable for gaseous C2H4 formation, suggesting that the promoter Pd or Ag has good selectivity towards C2H4 formation. The catalytic activity towards C2H4 formation follows the order PdCu(211) > PtCu(211) > NiCu(211) > RhCu(211) > AgCu(211) > AuCu(211) > Cu(211), indicating that the promoter can obviously increase the catalytic activity towards C2H4 formation compared to the Cu catalyst alone. Thus, the promoter Pd-modified Cu catalysts exhibit the highest catalytic activity and selectivity for C2H2 hydrogenation to C2H4. This work provides a method to evaluate and obtain the type of promoter with the best activity and selectivity in the selective hydrogenation of C2H2.