Adsorbed carbon formation and carbon hydrogenation for CO2 methanation on the Ni(111) surface:: ASED-MO study

Using the ASED-MO (Atom Superposition and Electron Delocalization-Molecular Orbital) theory, we investigated carbon formation and carbon hydrogenation for CO2 methanation on the Ni (111) surface. For carbon formation mechanism, we calculated the following activation energies, 1.27 eV for CO2 dissociation, 2.97 eV for the CO, 1.93 eV for 2CO dissociation, respectively. For carbon methanation mechanism, we also calculated the following activation energies, 0.72 eV for methylidyne, 0.52 eV for methylene and 0.50 eV for methane, respectively. We found that the calculated activation energy of CO dissociation is higher than that of 2CO dissociation on the clean surface and base on these results that the CO dissociation step are the rate-determining of the process. The C-H bond lengths of CH4 the intermediate complex are 1.21 angstrom, 1.31 angstrom for the (CH)-H-...(1), and 2.82 angstrom for the height, with angles of 105 degrees for angle H(1)CH and 98 degrees for H(1)CH(1).