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Elementary reaction
About: Elementary reaction is a research topic. Over the lifetime, 2972 publications have been published within this topic receiving 76110 citations.
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TL;DR: In this article, a steady-state microkinetic model is constructed with a piecewise adsorbate-adsorbate interaction model that explicitly includes the effects of adsorbates coverage on the rates and selectivities as well as the volcano plots are obtained.
26 citations
TL;DR: In this paper, the role of the co-adsorbed CO molecule played in the CO oxidation reaction on the basis of density functional theory (DFT) calculations, and the results indicate that the CO molecule at a triangular active site can induce the dissociation of the OCOO* intermediate via a tri-molecular reaction route.
Abstract: Using the icosahedra M13 (M = Au, Ag, Cu, Pt, Pd) and hetero-atom doped Au18M (M = Ag, Cu, Pt, Pd) clusters as model systems, we have systematically investigated the role of the co-adsorbed CO molecule played in the CO oxidation reaction on the basis of density functional theory (DFT) calculations. The results indicate that the co-adsorbed CO molecule at a triangular active site can induce the dissociation of the OCOO* intermediate via a tri-molecular reaction route. This mechanism is also validated on other larger single doped gold alloy clusters such as AunAg and AunCu (n = 32–34, 54). The underlying reason for promoting the oxidation effect of a co-adsorbed CO molecule is unraveled. It is found that the relatively weaker d–π* back bonding of CO on group 11 elements like Au, Ag and Cu may increase its electrophilic activity, which can facilitate the dissociation of nearby OCOO* intermediates. For the CO molecule that is bounded to the Pd and Pt atoms, it can also induce the dissociation of OCOO* intermediate, but shows weaker electrophilic activity. By explicitly considering the elementary reaction steps in a Kinetic Monte Carlo (KMC) simulation, we have shown that the tri-molecular reaction route is an alternative reaction channel of CO oxidation, which is competitive to the conventional bi-molecular route on a doped Au18M cluster.
26 citations
TL;DR: In this article, the behavior of rich hydrogen-air flames near the flammability limit is investigated using a computational model which involves the solution of the governing equations by implicit methods on an adaptive non-uniform grid, using detailed chemistry and a multi-species transport model.
Abstract: This paper presents an investigation of the behavior of rich hydrogen-air flames near the flammability limit. Ignition processes arc simulated using a computational model which involves the solution of the governing equations (for one-dimensional geometries) by implicit methods on an adaptive non-uniform grid, using detailed chemistry and a multi-species transport model. The reaction mechanism consists of 37 elementary reactions and 9 species. Calculations have been performed for different one-dimensional geometries. An investigation of the fundamental flammability limit {intrinsic to the combustion system itself), which is governed only by the physical and chemical processes in the gaseous mixture, is carried out by eliminating external factors such as heat loss, buoyancy, etc, in the calculations. Compulations have been performed for hydrogen-air mixtures of varying hydrogen content. Mixtures containing 75% or less hydrogen are found to be steadily propagating, whereas mixtures containing 82% o...
26 citations
TL;DR: In this article, steady-state measurements of resonance fluorescence have been used to determine the rate constants at 293 K for electronic (or reactive) quenching of excited OH A2Σ+ radicals with a variety of halogenocarbon molecules.
Abstract: Resonance fluorescence has been used to determine the rate constants k1 and k2(cm3 molecule–1 s–1)(1 σ) of elementary reactions of ground state OH X2Π radicals from 293 to 430 K: OH + CH3CCl3[graphic omitted]CH2CCl3+ H2O (1), log10k1=(–1162 ± 014)–(1394 ± 113)/2303 T; OH + CO [graphic omitted] CO2+ H (2), k2=(–1266 ± 012)–(88 ± 40)/2303 TIn addition, steady-state measurements of resonance fluorescence have been used to determine the rate constants at 293 K for electronic (or reactive) quenching of excited OH A2Σ+ radicals with a variety of halogenocarbon molecules Most of these excited-state quenching reactions occur with collision efficiencies approaching unity at 293 K, unlike the corresponding reactions involving ground state OH radicals
26 citations
TL;DR: In this paper, a mesoscopic stochastic model of the catalytic reaction 2CO+O2→2CO2 on the surface of a metal particle is considered, which is a Markovian chain of elementary reaction steps.
Abstract: A mesoscopic stochastic model of the catalytic reaction 2CO+O2→2CO2 on the surface of a metal particle is considered. The model is a Markovian chain of elementary reaction steps, which mimics the catalytic oxidation of CO on a nm-sized Pd particle. The model takes into account the effect of the particle size on the reaction rate and the role of temporal fluctuations of the concentrations of the reactants. The main goal of the paper is the comparison of the dynamics produced by the stochastic model and the deterministic model obtained via averaging of the master equation, while the catalyst particle size is reduced. Intrinsic fluctuations during the reaction are shown to change the reaction kinetics drastically for small metal particles with only several hundreds of surface atoms.
26 citations