First-Principles Microkinetic Study of NO Reduction on Cu Catalysts

Abstract

We have studied the NO reduction reaction on several Cu surfaces over a wide range of temperatures, with two dissociation pathways considered: monomer dissociation and dimer-mediated dissociation. Density functional theory was employed to estimate reaction energies, which were then used for microkinetic analysis. Under ultrahigh vacuum conditions, NO reduction occurs via a dimer-mediated dissociation pathway at lower temperatures, while NO is desorbed at higher temperatures. NO, N2, and N2O gases are formed, as observed in surface science experiments. Under catalytic conditions, dimer-mediated dissociation is the predominant reaction during the cold start period (T < 600 K), leading to high NO conversion. However, at typical three-way catalyst temperatures (600 K < T < 1200 K), monomer dissociation occurs along with NO desorption, leading to a decrease in NO conversion. Our result suggests that Cu is a promising catalyst for NO reduction, particularly at cold start temperatures.