Topic
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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01 Jan 2005
TL;DR: In this article, DeSain et al. present a simulation of a self-stabilized cool flame that survives for more than 10 seconds before dying away in microgravity.
Abstract: New results from experiments on propane + oxygen cool flame and two-stage ignitions in microgravity are reported. These include the occurrence of a “self-stabilized” cool flame that survives for more than 10 s, before dying away. Then, by integration of reaction–diffusion equations in a one-dimensional model, using a reduced kinetic scheme including very recent kinetic data for propylperoxy radical reactions derived by DeSain et al., simulations of these phenomena are presented and discussed. A validation of the reduced mechanism is given first, by simulation of multiple stage ignitions in closed vessels under spatially uniform conditions. The model is used to obtain a detailed spatial structure for temperature and selected chemical species during the development of cool flames, simulated with heat and mass diffusion in 1-D. Also included are novel approaches to the simulation of pressure change in a spherical vessel and the light output from CH 2 O ∗ chemiluminescence. The onset and spatial growth of the cool flame, and its ability to stabilize for a reasonable interval, is traced to the interaction between the elementary reactions that govern the negative temperature coefficient of reaction rate and the temperature field that is controlled by thermal diffusion to the reaction vessel walls. The vessel surface was assumed to be chemically inactive.
34 citations
TL;DR: A computational study using density functional theory is carried out to investigate the reaction mechanism of ethanol steam reforming on Co(0001) surfaces, and it is found that the reaction of formaldehyde yielding formic acid and hydrogen may not be an elementary reaction.
Abstract: A computational study using density functional theory is carried out to investigate the reaction mechanism of ethanol steam reforming on Co(0001) surfaces. The adsorption properties of the reactant, possible intermediates, and products are carefully examined. The reaction pathway and related transition states are also analyzed. According to our calculations, the reforming mechanism primarily consisting of dehydrogenation steps of ethanol, ethoxy, methanol, methoxy, and formic acid, is feasible on Co(0001) surfaces. It is also found that the reaction of formaldehyde yielding formic acid and hydrogen may not be an elementary reaction. The dehydrogenation of ethoxy possesses the highest barrier and is accordingly identified as the rate-determining step.
34 citations
TL;DR: In this article, the O(1D)+CH4 reaction has been investigated using a new universal crossed molecular beam apparatus, and the experimental results suggest that the main hydrogen loss channel in the CH4 reaction should be CH2OH (hydroxymethyl)+H, while the CH3O (methoxy)+H channel is at most a minor reaction channel.
Abstract: The O(1D)+CH4 reaction has been investigated using a new universal crossed molecular beam apparatus. Hydrogen atom elimination channel has been experimentally observed in this reaction. The pattern of dissociative ionization of the reaction products (from hydrogen loss channel) was compared with that of the methoxy (CH3O) radical produced from the photodissociation of CH3OH at 193 nm which has almost the same total energy deposition as the bimolecular reaction O(1D)+CH4. The experimental results suggest that the main hydrogen loss channel in the O(1D)+CH4 reaction should be CH2OH (hydroxymethyl)+H, while the CH3O (methoxy)+H channel is at most a minor reaction channel. This study provides an excellent experimental example of different dynamical behaviors exhibited in the unimolecular and bimolecular reactions of an essentially same chemical system (excited CH3OH) since the O(1D)+CH4 reaction likely occurs through the insertion mechanism.
34 citations
01 Apr 1994
TL;DR: In this paper, the absolute yields of the primary products of the reactions of CH2OH with F and Cl atoms and OH radicals were measured in the gas phase at room temperature using a discharge flow apparatus connected to a Far Infrared Laser Magnetic Resonance (FIR-LMR) spectrometer.
Abstract: The absolute yields of the primary products of the reactions of CH2OH with F and Cl atoms and OH radicals were measured in the gas phase at room temperature using a discharge flow apparatus connected to a Far Infrared Laser Magnetic Resonance (FIR-LMR) spectrometer. Quantitative determinations of the reaction pathways were carried out by employing reference reactions with known product yields. The measurements yielded the branching ratios for the following channels
Thus, the main reaction channels were found to be addition of the F, Cl, or OH, respectively, to the CH2 moiety followed by elimination of CO.
34 citations
TL;DR: In this article, the microscopic parameters of each model were calculated by density functional theory (DFT), and the elementary reaction pathways and thermodynamic parameters of hydroxyl groups were explored, and the results of intrinsic reaction coordinate (IRC) indicated that hydrogen captured by oxygen is endothermic, while the ·OH free radical capturing hydrogen is exothermic.
34 citations