Theoretical Study on Selective Hydrogenation of Acetylene Catalyzed by Ni/Cu modified ZSM-12 zeolite

Metal-loaded zeolites exhibit great potential in selective hydrogenation reactions due to their unique channel structure and acidity. In this study, density functional theory has been used to simulate the reaction mechanism of the selective hydrogenation of acetylene in the Cu\Ni loaded ZSM-12 zeolite. The results show that all four catalysts exhibit higher adsorption energies for C2H2 than for H2. In the adsorption process, the catalyst preferentially adsorbs H2, which would dissociate hydrogen into hydrogen ions. It can be observed that hydrogen ions are adsorbed near the Cu atom, while C2H2 deforms and then bonds with Cu atoms. The hydrogenation of ethylene to ethane is the rate-determining step in the hydrogenation reaction of acetylene. Among the catalytic reaction pathways, Ni/Cu-ZSM-12 has the best activity in catalyzing the selective hydrogenation of acetylene to ethylene. Through comparing the projected density of states(PDOS), HOMO, and LUMO orbitals of Cu atom and Ni/Cu atoms, it’s found that the doping of Ni atoms leads to the electron transfer and promotes the selective hydrogenation reaction of acetylene.