NO Reduction by CO on the Pt(100) Surface: A Density Functional Theory Study

Abstract

NO reduction belongs to the most important reactions in environmental and industrial catalysis. In this study the NO reduction accompanied by the simultaneous oxidation of CO over a platinum catalyst is investigated on the basis of ab-initio calculations. The whole reaction cycle is broken up into several reaction steps (CO and NO adsorption, NO dissociation, N2 desorption, CO oxidation, CO2 desorption). Each of these subprocesses is characterized by calculating transition state, adsorption/activation energy, prefactor, and rate constant, so that finally a consistent picture of the overall reaction on an atomistic scale is obtained. NO dissociation is found to be rate limiting with an activation barrier of Eact0=1.21 eV and a prefactor of ν=2.1·1012 ML·s−1; N2 desorption is an essentially barrierless process, while the CO oxidation step itself can be described by an activation energy of Eact0=0.83 eV and a prefactor of ν=2.0·1012 ML·s−1.