Oxygen-Coverage Effects on Molecular Dissociations at a Pt Metal Surface

Getman, Rachel B.; Schneider, William F.; Smeltz, Andrew; Delgass, W. Nicholas; Ribeiro, Fabio H.

doi:10.1103/physrevlett.102.076101

Cited by 104 publications

(131 citation statements)

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“…23,24 The strong repulsive interactions between the O-O and the O-NO pairs on Pt surfaces have been studied using first-principles calculations. [14][15][16]25,26 The through-space interactions are modeled herein by using a van der Waals (vdW) interaction model taken from the Merck molecular force field. 27 The through-surface interactions were calculated using a DFTbased bond order conservation (BOC) method.…”

Section: Simulation Methodsmentioning

confidence: 99%

First-Principles-Based Kinetic Monte Carlo Simulation of Nitric Oxide Reduction over Platinum Nanoparticles under Lean-Burn Conditions

Mei

Neurock

2010

Ind. Eng. Chem. Res.

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The kinetics for NO reduction over supported platinum under lean condition were investigated by firstprinciples-based kinetic Monte Carlo simulation over three-dimensional Pt nanoparticles. Model platinum nanoparticles with diameters ranging from 2.3 to 4.6 nm were constructed using a truncated octahedral cluster consisting of a two (100) facets and eight (111) facets. First-principles density functional theory (DFT) calculations were used to calculate the intrinsic kinetic parameters including the binding energies for all of the surface intermediates as well as the activation barriers and reaction energies that comprise the reaction mechanism over the (100) and (111) facets, as well as the (111)/(100) edge sites on the three-dimensional nanoparticle. Both intra-and inter-facet diffusion of adsorbates were included to model surface diffusion effects over the particle surface. The simulation results show that under lean conditions where there is excess oxygen, NO reduction to N 2 occurs solely on the (100) facets. The oxidation of NO to NO 2 , while much more favored on the (111) facets, can occur on both (100) and (111) facets. Only small amounts of N 2 O form over the (100) facets. The simulated apparent activation energies for N 2 and NO 2 formation over the entire particle are 45 and 42 kJ/mol, respectively. The latter is in agreement with experimentally measured value of 39 kJ/mol [Mulla, S. S., et al., Catal. Lett. 2005, 100, 267]. The effects of particle size on the activities of NO reduction to N 2 and NO oxidation to NO 2 depend upon the ratios of exposed surface sites. For the threedimensional model Pt nanoparticles examined here, the fractions of the (100) terrace sites are similar while the fraction of the (111) terrace sites increases with increasing particle size. As a result, the activity for NO reduction is somewhat insensitive to the particle size which symmetrically increases the numbers of (111) and (100) facets as the size increases. NO reduction, however, increases much more dramatically when the number of the (100) sites increases over the (111) sites. NO oxidation activity, on the other hand, appears to increase with increasing particle size regardless of the symmetry or shape of the particle as the reaction occurs predominantly over the (111) sites but can also take place on the (100) terrace sites. The structure insensitivity for NO oxidation is consistent with experimental results.

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Section: Simulation Methodsmentioning

confidence: 99%

First-Principles-Based Kinetic Monte Carlo Simulation of Nitric Oxide Reduction over Platinum Nanoparticles under Lean-Burn Conditions

Mei

Neurock

2010

Ind. Eng. Chem. Res.

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“…High coverages of oxygen drive the activation energy of O 2 dissociation up, so that this step is rate limiting. 25 Formation of NO 2 is fast because of the modest activation barrier which is relatively insensible to the O coverage. 25 In contrast to the very stable CO 2 molecule, NO 2 formation is reversible however and is an effective O atom donor to Pt(111).…”

Section: No Oxidation At Pt(111) Surfacementioning

confidence: 99%

“…25 Formation of NO 2 is fast because of the modest activation barrier which is relatively insensible to the O coverage. 25 In contrast to the very stable CO 2 molecule, NO 2 formation is reversible however and is an effective O atom donor to Pt(111). 25 The model that we have used is also much more complicated than the ZGB model, as there are lateral interactions.…”

Section: No Oxidation At Pt(111) Surfacementioning

confidence: 99%

“…25 In contrast to the very stable CO 2 molecule, NO 2 formation is reversible however and is an effective O atom donor to Pt(111). 25 The model that we have used is also much more complicated than the ZGB model, as there are lateral interactions.…”

Section: No Oxidation At Pt(111) Surfacementioning

confidence: 99%

“…26, besides adsorbed O adatoms we also have NO species at the surface. The system has been modeled by the reaction mechanism in 25 eV, respectively. The adsorption energy values of O 2 and NO 2 corresponded to the energy difference between gas phase species and two neighboring species at the surface.…”

Section: No Oxidation At Pt(111) Surfacementioning

confidence: 99%

See 2 more Smart Citations

Coupling of kinetic Monte Carlo simulations of surface reactions to transport in a fluid for heterogeneous catalytic reactor modeling

Schaefer

Jansen

2013

The Journal of Chemical Physics

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We have developed a method to couple kinetic Monte Carlo simulations of surface reactions at a molecular scale to transport equations at a macroscopic scale. This method is applicable to steady state reactors. We use a finite difference upwinding scheme and a gap-tooth scheme to efficiently use a limited amount of kinetic Monte Carlo simulations. In general the stochastic kinetic Monte Carlo results do not obey mass conservation so that unphysical accumulation of mass could occur in the reactor. We have developed a method to perform mass balance corrections that is based on a stoichiometry matrix and a least-squares problem that is reduced to a non-singular set of linear equations that is applicable to any surface catalyzed reaction. The implementation of these methods is validated by comparing numerical results of a reactor simulation with a unimolecular reaction to an analytical solution. Furthermore, the method is applied to two reaction mechanisms. The first is the ZGB model for CO oxidation in which inevitable poisoning of the catalyst limits the performance of the reactor. The second is a model for the oxidation of NO on a Pt(111) surface, which becomes active due to lateral interaction at high coverages of oxygen. This reaction model is based on ab initio density functional theory calculations from literature.

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