A MONTE-CARLO SIMULATION OF THE NO-PROMOTED PLATINUM(CO REACTION ON NA)

An irreversible surface reaction lattice-gas model for the reaction of carbon monoxide and nitric oxide on an Na-modified Pt(111) surface is presented. The effect of Na adatoms on the reaction kinetics is exami ned in terms of a ''local'' (i.e. short-range) model for alkali-promot ed NO dissociation. Within this framework we also study the effects of extending the range of alkali-induced NO dissociation from nearest ne ighbour to next nearest neighbour sites. The influence of varying amou nts of sodium on overall catalytic activity, reaction kinetics, and on the N-2/N2O selectivity are investigated by means of Monte Carlo simu lations. It is found that the principal features of recent experimenta l data involving electrochemical promotion by Na of the CO+NO reaction over Pt are satisfactorily accounted for in terms of this model. (C) 1998 Elsevier Science B.V. All rights reserved.