QUANTUM-CHEMICAL ANALYSIS OF THE ELEY-RIDEAL AND LANGMUIR-HINSHELWOODMECHANISMS OF THE CATALYTIC-OXIDATION OF CARBON-MONOXIDE ON THE NICKEL SURFACE

The studies concerned with the oxidation of carbon monoxide on the nic kel surface are reviewed. The Eley-Rideal (ER) collision and Langmuir- Hinshelwood (LH) adsorption mechanisms of the oxidation are analyzed. Calculations of the activation barriers of the oxidation of carbon mon oxide on the Ni (111), (100), and (110) faces were performed for the f irst time and involved optimization of the reaction paths by the colli sion and adsorption mechanisms. It is shown that on the Ni (111) and ( 110) faces the ER collision mechanism of the reaction is preferable wi th the activation barriers Delta E(dis)(O2) = 62 kJ/mole and Delta E(t rans)(O2) = 25 kJ/mole for Ni (111) and Delta E(dis)(O2) = 72 kJ/mole and Delta E(trans)(O2) = 20 kJ/mole for Ni (110); on the Ni (100) face , the LN adsorption mechanism with the activation barriers Delta E(dis )(O2) = 75 kJ/mole and Delta E(trans)(O2) = 42 kJ/mole is favored. Ana lysis of the potential barriers for the catalytic oxidation of carbon monoxide on the Ni surfaces suggests the LH mechanism to be preferenti al, although insignificant differences in the activation barriers can lead to the oscillatory reaction mechanism, which is confirmed experim entally. The calculations were performed by the LCAO MO SCF method in the MINDO/3 approximation.