Measurement of the rate constant of hydrogen atoms with carbon monoxide in tubular and jet stirred open reactors

1977 ◽  
Vol 6 (2) ◽  
pp. 225-230 ◽  
Author(s):  
J. Lede ◽  
J. Villermaux

1989 ◽  
Vol 11 (3) ◽  
pp. 235-244 ◽  
Author(s):  
V. Sandhu ◽  
O. P. Strausz ◽  
T. N. Bell


1972 ◽  
Vol 76 (22) ◽  
pp. 3301-3302 ◽  
Author(s):  
David H. Volman ◽  
Robert A. Gorse


1978 ◽  
Vol 56 (20) ◽  
pp. 2638-2645 ◽  
Author(s):  
D. W. Grattan ◽  
K. O. Kutschke

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.





A detailed study has been made of the products from the reaction between hydrogen atoms and ethylene in a discharge-flow system at 290 ± 3 K. Total pressures in the range 8 to 16 Torr (1100 to 2200 Nm -2 ) of argon were used and the hydrogen atom and ethylene flow rates were in the ranges 5 to 10 and 0 to 20 μ mol s -1 , respectively. In agreement with previous work, the main products are methane and ethane ( ~ 95%) together with small amounts of propane and n -butane, measurements of which are reported for the first time. A detailed mechanism leading to formation of all the products is proposed. It is shown that the predominant source of ethane is the recombination of two methyl radicals, the rate of recombination of a hydrogen atom with an ethyl radical being negligible in comparison with the alternative, cracking reaction which produces two methyl radicals. A set of rate constants for the elementary steps in this mechanism has been derived with the aid of computer calculations, which gives an excellent fit with the experimental results. In this set, the values of the rate constant for the addition of a hydrogen atom to ethylene are at the low end of the range of previously measured values but are shown to lead to a more reasonable value for the rate constant of the cracking reaction of a hydrogen atom with an ethyl radical. It is shown that the recombination reaction of a hydrogen atom with a methyl radical, the source of methane, is close to its third-order region.



Lead atoms, present as a trace additive in a series of premixed H 2 –N 2 –O 2 flames, were excited to the 7 3 P o 1 state by 405.8 nm radiation from a nitrogen-pumped dye laser. Rate constants for spin-orbit relaxation to the 7 3 P o 0 state were obtained separately for collisions with atomic hydrogen and for collisions with the bulk flame gas, by measuring the relative intensities of fluorescence at 364.0 and 368.3 nm as a function of distance from the reaction zone in each flame. For hydrogen atoms the rate constant is typically 1 x 10 -9 cm 3 molecule -1 s -1 , decreasing with increasing temperature; for the bulk flame gas the rate constant is typically 1 x 10 -11 cm 3 molecule -1 s -1 , increasing with increasing temperature. Numerical calculations for model systems, with the use of Morse and Lennard-Jones potentials to describe the interaction of the colliding species, show that the negative temperature coefficient found for atomic hydrogen can be attributed to the crossing of attractive potential curves, corresponding to bound excited states of PbH.



1959 ◽  
Vol 12 (4) ◽  
pp. 533 ◽  
Author(s):  
JD Blackwood ◽  
FK McTaggart

Wood chars were reacted at atmospheric temperature with hydrogen atoms, oxygen atoms and carbon monoxide, hydrogen atoms and hydroxyl radicals, produced by the action of a radio frequency field on hydrogen, carbon dioxide, and water vapour respectively. The chars were prepared at different temperatures and contained different amounts of oxygen. The experimental results showed that the gases must be present in the atomic form before reaction with the carbon can take place and that such species react on the carbon-surface independently of active sites. In normal gasification processes the atomic species appear to be produced at active centres, which for the chars used could be correlated with specific oxygen groups remaining in the carbon. It is suggested that these groupings may have a pyran structure. An explanation has been put forward for the retardation of the carbon-water vapour reaction by hydrogen, and of the carbon-carbon dioxide reaction by carbon monoxide. These are considered as due to reverse mechanisms which decrease the concentration of the atomic species and not to the blocking of active sites by adsorption of the retardant.



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