Rhodium plays a key role in three-way catalysts to control NOx emissions in gasoline engines primarily through the reduction of NO by CO. Despite extensive investigation, there remains uncertainty ...

Low-Temperature Ammonia Production during NO Reduction by CO Is Due to Atomically Dispersed Rhodium Active Sites

In the NO + CO catalytic reaction on Rh(111), it is known from experiments that N2O and N2 are formed at low and high reaction temperatures, respectively, although the mechanism has not been fully ...

First-Principles Microkinetic Analysis of NO + CO Reactions on Rh(111) Surface toward Understanding NOx Reduction Pathways

Reaction of NO molecule on M13 and M55 clusters (M = Ru, Rh, Pd, and Ag) was theoretically investigated to elucidate why its reaction behavior depends on the position of metal element in the period...

Reaction Behavior of the NO Molecule on the Surface of an Mn Particle (M = Ru, Rh, Pd, and Ag; n = 13 and 55): Theoretical Study of Its Dependence on Transition-Metal Element

A comparative turnover frequency (TOF) study for structure-sensitive CO–NO reactions between overlayer (thin-film) and nanoparticle Rh catalysts was performed using a combined experimental and theoretical approach. Two types of honeycomb catalysts were prepared: one by the arc-plasma deposition of a 3 nm Rh overlayer having a (111) preferential orientation atop a 20-μm Fe–Cr–Al metal foil and the other by a conventional wet coating of Rh/ZrO2 powders comprised of Rh nanoparticles onto a cordierite honeycomb. The reaction rate of the overlayer was found to be more superior to the nanoparticles, despite a smaller surface area, as the TOF was 14-fold greater on the overlayer than on the nanoparticle. In situ infrared spectroscopy suggested that a hollow-site NO formed onto the overlayer in contrast to the bridge- and on-top-NO adsorptions on the nanoparticles. The energy barriers for surface reactions of adsorbed NO molecules were analyzed using a density functional theory based molecular dynamics approach f...

High Turnover Frequency CO–NO Reactions over Rh Overlayer Catalysts: A Comparative Study Using Rh Nanoparticles

In nanocatalysis, growing attention has recently been given to investigation of energetically low-lying structural isomers of atomic clusters, because some isomers can demonstrate better catalytic ...

Combined Automated Reaction Pathway Searches and Sparse Modeling Analysis for Catalytic Properties of Lowest Energy Twins of Cu13.

The reduction of NOx is crucial for reducing air pollution from vehicle exhaust. In the presence of Rh-based catalysts, the dissociation of NO and the formation of N2O and N2 constitute the important elementary steps of NOx reduction. The present study used density functional theory (DFT) to investigate the catalytic performances of the Rh(111) surface and Rh55 and Rh147 clusters toward these elementary reactions. The NO dissociation reaction was found to have minimum activation barriers (Ea) of 0.63, 0.68, and 1.25 eV on Rh55, Rh147, and Rh(111), respectively. Therefore, it is the fastest on small Rh clusters. In contrast, the N2 formation reaction is relatively inefficient on small clusters, with corresponding Ea values of 2.14, 1.79, and 1.71 eV. Because of the stronger binding of N atoms to the Rh clusters than to the Rh surface, N2 formation through the recombination of N atoms has a higher Ea value on Rh clusters. The calculated reaction rate constants confirmed that small Rh clusters are less react...

Fumiko Deushi

Papers

Density Functional Theory Analysis of Elementary Reactions in NOx Reduction on Rh Surfaces and Rh Clusters