In this paper, by the density functional theory (DFT) calculations we show that the copper nanocluster can be used as catalyst for the hydrogenation of acetylene and ethylene. Since the nature of dissociation of hydrogen molecule on the copper nanocluster is the governing step for the hydrogenation reaction, the adsorptionand completedissociation of H2 on the Cu11 nanocluster is investigatedat PBE-G/DNP-ECP level of theory. The results show that H2 is adsorbed dissociatively on the Cu11 nanocluster. To examine the activity of copper nanocluster as a catalyst for the hydrogenation reaction, the hydrogenations of acetylene and ethylene are investigated on the free Cu11 nanocluster, due to its highest adsorption energies for hydrogen, acetylene and ethylene adsorptions. In the presence of the Cu11 nanocluster as a catalyst, acetylene and ethylene can be hydrogenated to ethylene and ethane, respectively. These reactions are exothermic with the total reaction energies of247.61 and174.01 kJ/mol for hydrogenation of acetylene and ethylene, respectively. One of the interesting features of this catalyst is that the energy of acetylene adsorption on Cu112H complex is higher than the energy of ethylene adsorption. It seems that Cu11 nanocluster can be used as catalyst for the selective hydrogenation of acetylene. Also, we choose graphene as a support for copper nanocluster and the hydrogenation of acetylene and ethylene on graphene-supported Cu11 nanocluster are investigated. Based on our DFT calculations, we suggest graphene-supported Cu11 nanoclusters as candidates with good activity and selectivity for the acetylene hydrogenation reaction.
