Kinetic study of the “surface explosion” phenomenon in the NO+CO reaction on Pt(100) through dynamic Monte Carlo simulation

Abstract

The extremely narrow production peak of N2 and CO2 which occurs in the reaction of NO+CO on Pt(100), a phenomenon known as "surface explosion," is studied using a dynamic Monte Carlo method on a square lattice at low pressure under isothermal conditions. This analysis incorporates recent experimental evidence obtained for the same reaction on a Rh(111) surface, which has shown that N2 production occurs either from the classical N+N recombination step or by the formation and successive decay of a (N-NO)* intermediary species. Moreover, the NO dissociation rate is inhibited by coadsorbed NO and CO molecules and is enhanced both by the presence of empty sites and adsorbed N atoms as nearest neighbors. These effects are taken into account in this study, along with the experimental adsorption, desorption, and diffusion rates of the reactants. The "explosive" phenomenon is analyzed through the evolution over time of an adsorbed NO+CO monolayer at a fixed temperature of 400 K. Furthermore, as the diffusion processes of the adsorbates are included, cellular structures are observed. Our simulations show quantitative agreement in the position of maxima with those obtained through experiments using isothermal desorption mass spectroscopy.

Oxidation of propylene over Pd(5 5 1): Temperature hysteresis induced by carbon deposition and oxygen adsorption

“…CO formation showed a sharp intense peak with a maximum at ∼520 K. The full width at half maximum of the peak was only 35 degrees, and, hence, it can be called a "surface explosion" [24][25][26]. Surface explosions have been studied in detail for the NO + CO reaction over Pt(1 0 0), where the platinum surface undergoes a change between a state with a low catalytic activity (where a high adsorbate coverage inhibits the dissociation of adsorbed NO) and a state with a high catalytic activity (where a low surface coverage allows NO dissociation) [25]. Most likely that in our case, the surface at low temperatures was blocked by carbon atoms and no reaction products were formed; whereas at higher temperatures, carbon atoms started to react with oxygen atoms to produce free sites for further oxygen adsorption and reaction.…”

Dynamic monte carlo simulations of NO decomposition on Pt(100): Temperature‐programmed desorption spectra

“… MC simulations with β = 12.5 K/s. The dark circles are the data from Ref 19,. and open circles are MC outcomes averaged for an initial coverage θ NO = 0.2.…”

“…Another approach is to use Monte Carlo simulations17–19. These simulations are relevant when studying small systems, because they incorporate the discreteness of reactive events in an intrinsic manner, and spatial fluctuations and correlations are taken into account.…”

Catalysis of Cu Cluster for NO Reduction by CO: Theoretical Insight into the Reaction Mechanism

“…Among these three reactions, NO reduction by CO has been investigated well both in experiments 2−5 and in theoretical calculations. 6−9 In these studies, the N–O bond cleavage was considered to occur on Rh, 2,3,9 Pt, 6,8 and Pd 5 as one of the key elementary steps.…”

“…13,14 In these studies, the dissociative NO adsorption was proposed as an important initial step like in the NO–CO reaction by Rh, Pt, and Pd catalysts. 2,3,5,6,8,9 Also, Ag nanoscale particles were experimentally reported to be active for NO decomposition. 15−18 Pioneering theoretical research reported that the NO decomposition did not occur through dissociative NO adsorption but through NO dimerization.…”