Surface intermediates in the catalytic reaction of NO+H2 on Rh studied by method of interacting bonds calculations

The semi-empirical method of interacting bonds was used to clarify the mechanism of oscillatory behavior of the catalytic system (NO + H-2)/Rh. Various rhodium planes and surface defect regions were characterized by the strength of the nitrogen bond to the surface, the stability of the adsorbed NHn species (n = 0, 1, 2, 3), and the reactivity of NH, species towards hydrogen. Calculations admit the earlier suggested reaction mechanism, which attributes the surface wave propagation to the intermediate formation of NH, species. The activity of the rhodium surface in oscillations is expected to increase in a row of planes: (100) < (111) < (335). The activity of Rh(335) single crystal in the reaction rate oscillations is probably governed by the presence (in contrast to ideal terraces) of gradient and broad range of the reaction intermediate properties.