Author
D.R. Jenkins
Bio: D.R. Jenkins is an academic researcher from Royal Dutch Shell. The author has contributed to research in topics: Hydrogen & Bond-dissociation energy. The author has an hindex of 8, co-authored 10 publications receiving 321 citations.
Topics: Hydrogen, Bond-dissociation energy, Catalysis, Oxide, Metal
Papers
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TL;DR: In this paper, a semiquantitative mechanism was proposed for the alkaline earth metals; its basis is that these metals undergo a homogeneous, gas-phase reaction with flame gases to produce hydroxyl radicals which rapidly remove soot or soot precursors.
109 citations
TL;DR: For calcium, strontium and barium, the bond dissociation energies of the monohydroxides were respectively 104, 103, and 114 kcal mole-1 and of the dihydroxides are 204, 202, and 213 kcal mole−1 as discussed by the authors.
Abstract: Atomic absorption spectroscopy has been used to measure the concentration of alkaline earth metal atoms as a function of hydrogen atom concentration in fuel-rich hydrogen + oxygen + nitrogen flames. In these flames, oxide formation is unimportant but both monohydroxides and dihydroxides are formed in significant amounts. For calcium, strontium and barium, the bond dissociation energies of the monohydroxides are respectively 104, 103, and 114 kcal mole–1 and of the dihydroxides are 204, 202 and 213 kcal mole–1.
48 citations
TL;DR: In this article, the rate of recombination of hydrogen atoms in fuel-rich hydrogen/oxygen/nitrogen flames containing metal additives has been measured using the lithium/lithium hydroxide method to monitor hydrogen atom concentrations.
Abstract: The rate of recombination of hydrogen atoms in fuel-rich hydrogen/oxygen/nitrogen flames containing metal additives has been measured using the lithium/lithium hydroxide method to monitor hydrogen atom concentrations. It is found that the rate of the recombination reaction is accelerated by the addition of alkaline earth metals. The preferred mechanism for catalysis is via the cycle of reactions: MOH + H →MO + H2(7), MO + H2O(+X)→M(OH)2(+X)(8), M(OH)2+ H⇌MOH + H2O (–5), and the rate of the catalyzed recombination is given by the expression [graphic omitted] Values of k7 and lower limits of k8 have been determined for calcium, strontium and barium at 1570 K and 1800 K. The upper limit for the catalysis to be effective is about 2000 K. This is determined by the increase of K5 with temperature.
43 citations
TL;DR: In this paper, atomic absorption spectroscopy has been used to measure the concentrations of each of the alkali metals as a function of hydrogen atom concentration in hydrogen-rich, hydrogen + oxygen + nitrogen flames.
Abstract: Atomic absorption spectroscopy has been used to measure the concentrations of each of the alkali metals as a function of hydrogen atom concentration in hydrogen-rich, hydrogen + oxygen + nitrogen flames. The flame temperatures were chosen so that ionization was negligible. From the measurements, values for the bond dissociation energies of the hydroxides were obtained as follows: LiOH, 105 ± 2; NaOH, 80 ± 2; KOH, 85 ± 2; RbOH, 87 ± 2; and CsOH, 90 ± 2 kcal mole–1.
36 citations
TL;DR: In this paper, an analysis of the factors that determine the signal-to-noise ratio of the measurement of the fluorescence of metallic elements in flames is made, with particular attention paid to the effect of the type of flame used on the intensity of fluorescence.
30 citations
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TL;DR: In this article, the authors present a mechanism for soot formation in a premixed laminar flame, where chemiions are assumed to be the precursor on which the free radicals, polyacetylenes, and polycyclic aromatic hydrocarbons repeatedly add in fast ion-molecule reactions.
351 citations
TL;DR: In this paper, the potential of catalytic systems in automobile emission control is discussed, and a review of the catalytic technology applicable in each case, the operating principles and performance characteristics, durability aspects and considerations regarding the interactions between catalyst performance and engine management are presented.
340 citations
TL;DR: The mechanism of atom formation for a number of elements in a Perkin-Elmer heated graphite atomizer, HGA 2100, has been studied using a combined thermodynamic and kinetic approach as discussed by the authors.
Abstract: The mechanism of atom formation for a number of elements in a Perkin-Elmer heated graphite atomizer, HGA 2100, has been studied using a combined thermodynamic and kinetic approach. Assuming that an analyte surface-gas phase equilibrium exists within the furnace and the production of observable atoms is characterized by a unimolecular rate constant, a plot of the logarithm of the absorbance as a function of the inverse of the absolute temperature yields a straight line from which the activation energy, E/sub a/, of the limiting step in the atomization pathway can be obtained. These E/sub a/ values reveal that three major atomization mechanisms are operative: thermal dissociation of the analyte oxide or halide, and carbon reduction of the oxide followed by atomization of the free metal.
273 citations
TL;DR: In this article, a detailed chemical kinetic mechanism was developed for C1 and C2 fluorinated hydrocarbon destruction and flame suppression using ab initio molecular orbital theory and RRKM and QRRK methods.
236 citations