The Kinetics of the Reaction of Gaseous Hydrogen Atoms with Oxygen on Cu(111) Surfaces toward Water

2001 ◽  
Vol 105 (35) ◽  
pp. 8369-8374 ◽  
Author(s):  
Th. Kammler ◽  
J. Küppers
Keyword(s):  
Gaseous Hydrogen ◽  
Hydrogen Atoms ◽  
Kinetics Of

Reaction kinetics of gaseous hydrogen atoms with graphite

1969 ◽  
Vol 73 (5) ◽  
pp. 1348-1351 ◽  
Author(s):  
Bernard J. Wood ◽  
Henry Wise
Keyword(s):  
Reaction Kinetics ◽  
Gaseous Hydrogen ◽  
Hydrogen Atoms ◽  
Kinetics Of

Reactions of hydrogen atoms with hexafluoroacetone

1978 ◽  
Vol 56 (20) ◽  
pp. 2638-2645 ◽  
Author(s):  
D. W. Grattan ◽  
K. O. Kutschke
Keyword(s):  
Rate Constant ◽  
Cross Sections ◽  
The Other ◽  
Hydrogen Atoms ◽  
Kinetics Of

Attempts were made to study the kinetics of the reaction of atomic H with (CF3)2CO vapour (HFA). Atomic H was generated from H2 by mercury photosensitization in the presence of C2H4 and HFA but the system was complicated by the loss of C2H5 radicals by addition to HFA and the kinetic results were intractable. When atomic H was generated from C3H8, the kinetics again were obscured by some unidentified reaction(s) which became more important at higher [HFA]/[C3H8]. An estimate of the rate constant for the addition of H to HFA obtained at low [HFA]/[C3H8] yielded k9 = 8.5 × 105 l mol−1 s−1. Trifluoroacetaldehyde was identified with some reliability but many of the other heavier products formed in the H2 + HFA reaction could not be identified. Quenching cross-sections were determined for C2H4, C3H8, C4H10, and HFA relative to that for N2O.

Reactions of free radicals with aromatic compounds in the gaseous phase. I. Kinetics of the reaction of methyl radicals with toluene

1964 ◽  
Vol 17 (12) ◽  
pp. 1329 ◽  
Author(s):  
MFR Mulcahy ◽  
DJ Williams ◽  
JR Wilmshurst
Keyword(s):  
Flow System ◽  
Methyl Radicals ◽  
Methyl Radical ◽  
Hydrogen Atoms ◽  
Methyl Group ◽  
Benzyl Radical ◽  
Toluene Molecule ◽  
Benzyl Radicals ◽  
Butyl Peroxide ◽  
Kinetics Of

The kinetics of abstraction of hydrogen atoms from the methyl group of the toluene molecule by methyl radicals at 430-540�K have been determined. The methyl radicals were produced by pyrolysis of di-t-butyl peroxide in a stirred-flow system. The kinetics ,agree substantially with those obtained by previous authors using photolytic methods for generating the methyl radicals. At toluene and methyl-radical concentrations of about 5 x 10-7 and 10-11 mole cm-3 respectively the benzyl radicals resulting from the abstraction disappear almost entirely by combination with methyl radicals at the methylenic position. In this respect the benzyl radical behaves differently from the iso-electronic phenoxy radical, which previous work has shown to combine with a methyl radical mainly at ring positions. The investigation illustrates the application of stirred-flow technique to the study of the kinetics of free-radical reactions.

scholarly journals Long-Time Non-Debye Kinetics of Molecular Desorption from Substrates with Frozen Disorder

Molecules ◽  
2020 ◽  
Vol 25 (16) ◽  
pp. 3662
Author(s):  
Victor N. Bondarev ◽  
Volodymyr V. Kutarov ◽  
Eva Schieferstein ◽  
Vladimir V. Zavalniuk
Keyword(s):  
Second Order ◽  
Order Effects ◽  
Desorption Kinetics ◽  
Hydrogen Atoms ◽  
Closed Expression ◽  
Hydrogen Molecules ◽  
Long Time ◽  
Second Order Effects ◽  
Molecular Desorption ◽  
Kinetics Of

The experiments on the kinetics of molecular desorption from structurally disordered adsorbents clearly demonstrate its non-Debye behavior at “long” times. In due time, when analyzing the desorption of hydrogen molecules from crystalline adsorbents, attempts were made to associate this behavior with the manifestation of second-order effects, when the rate of desorption is limited by the rate of surface diffusion of hydrogen atoms with their subsequent association into molecules. However, the estimates made in the present work show that the dominance of second-order effects should be expected in the region of times significantly exceeding those where the kinetics of H2 desorption have long acquired a non-Debye character. To explain the observed regularities, an approach has been developed according to which frozen fluctuations in the activation energy of desorption play a crucial role in the non-Debye kinetics of the process. The obtained closed expression for the desorption rate has a transparent physical meaning and allows us to give a quantitative interpretation of a number of experiments on the desorption kinetics of molecules not only from crystalline (containing frozen defects) but also from amorphous adsorbents. The ways of further development of the proposed theory and its experimental verification are outlined.

Kinetics of hot hydrogen atoms from hydrogen sulfide photodissociation at 1850 A

1969 ◽  
Vol 73 (4) ◽  
pp. 1158-1160 ◽  
Author(s):  
L. E. Compton ◽  
J. L. Gole ◽  
Richard McKelvy Martin
Keyword(s):  
Hydrogen Sulfide ◽  
Hydrogen Atoms ◽  
Kinetics Of

scholarly journals On the catalytic dehydrogenation of naphthenes I. Kinetic study

1947 ◽  
Vol 190 (1022) ◽  
pp. 289-308 ◽  
Keyword(s):  
Activation Energy ◽  
Main Reaction ◽  
Ethyl Benzene ◽  
Slow Step ◽  
Side Reactions ◽  
Catalytic Dehydrogenation ◽  
Hydrogen Atoms ◽  
Stationary Concentration ◽  
Methyl Cyclohexane ◽  
Kinetics Of

The kinetics of the dehydrogenation of naphthenes over a chromium oxide supported on alumina catalyst at temperatures of 400° C and above has been investigated. Cyclohexene has been detected and estimated in the products from cyclohexane, and it has been shown that side reactions producing olefine other than cyclohexene proceed at only 0.01 of the speed of the main reaction at 450° C. If the contact time is sufficiently long a stationary concentration of olefine is established. The linear nature of the plot of the reciprocal of the rate against the reciprocal of the pressure for cyclohexane and methyl cyclohexane has been demonstrated experimentally for the stationary state conditions, while the intercepts and slopes have been identified with functions of the rate constants. As a result of the study of the rate of dehydrogenation of cyclohexene it is concluded that the loss of the first pair of hydrogen atoms from cyclohexane is the slow step in the reaction. An activation energy of 36 kcal./g. mol. has been obtained for this step. The variation of the stationary olefine con­centration with temperatures indicates that for cyclohexane and methyl cyclohexane the loss of the first pair of hydrogen atoms is the step with the highest activation energy. The variation of rate with pressure and the behaviour when nitrogen and benzene are mixed with the reactants all prove that benzene and hydrogen act mainly as diluents. Evidence is presented from the failure to attain thermodynamic equilibrium between ethyl benzene, styrene and hydrogen during the dehydrogenation of ethyl cyclohexane for a stepwise mechanism in which a large proportion of the molecules evaporate from the surface after the loss of the first pair of hydrogen atoms.

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