CH + H2 (+M) -> CH3 (+M)
k_o = 4.83E+25 T^(-2.8) exp(-590 cal/mol /RT) cm^6/mol^2
s
k_inf = 1.98E+12 T^(.43) exp(370 cal/mol /RT)cm3/mol
s
F_cent = (1-0.578) exp(-T/122) + 0.578 exp(-T/2535) +
exp(-9365/T)
Third-body efficiencies:
N2 1.0
H2 Enhanced by 2.0
H2O Enhanced by 6.0
CH4 Enhanced by 2.0
CO Enhanced by 1.5
CO2 Enhanced by 2.0
C2H6 Enhanced by 3.0
AR Enhanced by 0.7
SOURCE:
- Two channel RRKM calculations for CH3 decomposition, following the
work of Wagner and Harding (1992). (A. F. Wagner, private communication,
1996) The related reactions of this system are 50
H + CH2 (+M) = CH3 (+M), and the chemical activation 126
CH + H2 = H + CH2.
< delta-E> (average energy transferred per collision) = 0.30 kcal/mol
The Lennard-Jones parameters: sigma (CH3-N2) = 3.78 A, epsilon = 103 K
I+/I (used to compute the Waage-Rabinovitch correction for rotational energy)
= 6.8
v = 3184, 3184, 3000, 1383, 1383, 580 cm^(-1)
COMMENTS:
- The recent k_inf measurements of Brownsword et al (1997) up to 744K
are just 10% greater than this expression. Values for k_o(Ar) agree within
20%.
- A comparison with high temperature data for the reverse decomposition
reaction, k_o in Ar, is shown in the figure.
- The pressure broadening is expressed in the Troe
form.in
- Included in the mechanism for version 3.0, where it served as an optimization
variable. The final rate expressions are 0.50 times the original base values.
REFERENCES:
- Rohrig et al (1997)
- Rohrig, M., Petersen, E.L., Davidson, D.F., Hanson, R.K., and Bowman,
C.T. (1997) Int. J. Chem. Kinet. 29 , 781.
- Brownsword et al (1997)
- Brownsword, R.A., Canosa, A., Rowe, B.R., Sims, I.R., Smith, I.W.M.,
Stewart, D.W.A., Symonds, A.C., and Travers, D. (1997) J. Chem. Phys.
106, 7662.
- Markus et al. (1996)
- Markus, M.W., Roth, P., and Just, Th. (1996) Int. J. Chem. Kinet.
28 , 171.
- Lim and Michael (1994)
- Lim, K.P., and Michael, J.V. (1994) 25th Symposium (International)
on Combustion, p. 713.
- Kiefer and Kumaran (1993)
- Kiefer, J.H. and Kumaran S.S. (1993) J. Phys. Chem. 97,
414.
- Dean and Hanson (1992)
- Dean, A.J., and Hanson, R.K. (1992) Int. J. Chem. Kinet. 24
, 517.
- Markus et al. (1992)
- Markus, M.W., Woiki, D., and Roth P. (1992) 24th Symposium (International)
on Combustion, p. 581.
- Troe (1977)
- Troe, J. (1977) J.Chem.Phys. 66, 4745.
- Wagner and Harding (1992)
- Wagner, A.F., and Harding, L.B. (1992) ACS Symp. Ser. 502,
48.
PRESSURE = 0.1 atm N2
______________________________________________________________________
Temp delta-S delta-H kf kr Keq
(K) (cal/mol K) (kcal/mol) ----(mol,cm3,s)----- (cm3/mol)
______________________________________________________________________
300 -27.5 -110.8 4.87E+12 1.32E-64 3.69E+76
500 -29.5 -111.5 1.26E+12 6.20E-34 2.04E+45
1000 -31.2 -112.7 1.33E+11 2.07E-11 6.41E+21
1500 -31.6 -113.2 3.13E+10 1.20E-04 1.01E+14
2000 -31.6 -113.3 1.08E+10 7.85E-01 1.37E+10
2500 -31.6 -113.2 4.71E+09 6.75E+01 6.96E+07
3000 -31.5 -113.0 2.40E+09 1.13E+04 2.13E+06
______________________________________________________________________
PRESSURE = 1 atm N2
______________________________________________________________________
Temp delta-S delta-H kf kr Keq
(K) (cal/mol K) (kcal/mol) ----(mol,cm3,s)----- (cm3/mol)
______________________________________________________________________
300 -27.5 -110.8 1.57E+13 4.24E-64 1.85E+76
500 -29.5 -111.5 6.85E+12 3.36E-33 1.02E+45
1000 -31.2 -112.7 1.08E+12 1.68E-10 3.21E+21
1500 -31.6 -113.2 2.69E+11 2.66E-03 5.05E+13
2000 -31.6 -113.3 9.45E+10 6.90E+00 6.85E+09
2500 -31.6 -113.2 4.17E+10 6.00E+02 3.48E+07
3000 -31.5 -113.0 2.15E+10 1.01E+04 1.07E+06
______________________________________________________________________
PRESSURE = 10 atm N2
______________________________________________________________________
Temp delta-S delta-H kf kr Keq
(K) (cal/mol K) (kcal/mol) ----(mol,cm3,s)----- (cm3/mol)
______________________________________________________________________
300 -27.5 -110.8 3.15E+13 8.50E-64 3.69E+76
500 -29.5 -111.5 1.81E+13 8.85E-33 2.04E+45
1000 -31.2 -112.7 5.65E+12 8.80E-10 6.41E+21
1500 -31.6 -113.2 1.87E+12 1.85E-02 1.01E+14
2000 -31.6 -113.3 7.20E+11 5.25E+01 1.37E+10
2500 -31.6 -113.2 3.30E+11 4.74E+03 6.96E+07
3000 -31.5 -113.0 1.75E+11 8.25E+04 2.13E+06
______________________________________________________________________
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