H + HCO (+M) -> CH2O (+M)

k_inf = 1.09E+12 T^0.48 exp(260 cal/mol /RT) cm3/mol s

F_cent = (1-0.782) exp(-T/271) + 0.782 exp(-T/2755) + exp(-6570/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:

From 2 channel RRKM calculations that approximately fit the 1 atm results of Just (1981), Dean et al. (1980), and Forst (1983).

Parameters for 2-channel RRKM calculations of formaldehyde decomposition:

<delta-E>= 0.30 kcal/mol; no Waage-Rabinovitch centrifugal correction
The Lennard-Jones parameters: sigma (CH2O-Ar) = 3.70 A, epsilon = 180 K
Active molecular K-rotor 1.8 amu-A^2, sigma = 1
v = 2843, 2766, 1746, 1500, 1247, 1164 cm^(-1)
Adiabatic I = 149, 130 amu-A^2; sigma = 2

Transition state 1. H2 + CO

<delta-E>(0 K) = 79.5 kcal/mol (Ho et al. (1982))
Adiabatic I+ = 149, 130 amu-A^2; sigma = 2
Active molecular K-rotor 1.8 amu-A^2, sigma = 1
v = 3125, 1830, 1523, 936, 840 cm^(-1)

Transition state 2. H + HCO

<delta-E>(0K) = 86.6 kcal/mol
Adiabatic I+ = 87.7, 87.7 amu-A^2; sigma = 1
Active molecular K-rotor 1.8 amu-A^2, sigma = 1
v = 3000, 1860, 1080 cm^(-1)
Hindered 2-D rotor I = 1.4 amu-A^2 (90%)

The pressure broadening is expressed in the Troe form.

Comparison of decomposition, k_o in Ar at 2000 K (cm3/mol s)

Reference	H2 + CO	H + HCO
GRI-Mech	1.6E8	3.0E7
Just (1981)	2.2E8	2.5E7
Dean et al. (1980)		4.6E7
Forst (1983)	1.3E8	4.3E7

REFERENCES:

Just (1981)

Just, Th. (1981) in Shock Waves in Chemistry, A. Lifshitz, ed., Marcel Dekker, NY, p. 303.

Dean et al. (1980)

Dean, A.M., Johnson, R.L., and Steiner, D.C. (1980) Combust. Flame 37, 41.

Forst (1983)

Forst, W. (1983) J. Phys. Chem. 87, 4489.

Ho et al. (1982)

Ho, P., Bamford, D.M., Buss, R.J., Lee, Y.T., and Moore, C.B. (1982) J. Chem. Phys. 76, 3630.

                        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       -28.8       -88.1    1.99E+11    1.04E-51    1.91E+62
     500       -31.0       -89.0    8.34E+10    1.58E-26    5.28E+36
    1000       -32.9       -90.3    1.41E+10    4.98E-08    2.84E+17
    1500       -33.3       -90.8    4.15E+09    3.84E-02    1.08E+11
    2000       -33.4       -90.9    1.66E+09    2.34E+01    7.08E+07
    2500       -33.4       -90.8    8.00E+08    8.75E+02    9.14E+05
    3000       -33.3       -90.7    4.39E+08    8.39E+03    5.23E+04
______________________________________________________________________


                        PRESSURE = 1 atm N2  
______________________________________________________________________
    Temp      delta-S     delta-H      kf          kr         Keq     
     (K)    (cal/mol K)  (kcal/mol) ----(mol,cm3,s)-----   (cm3/mol)  
______________________________________________________________________
                                                                      
     300       -28.8       -88.1    1.58E+12    8.30E-51    1.91E+62
     500       -31.0       -89.0    7.51E+11    1.42E-25    5.28E+36
    1000       -32.9       -90.3    1.34E+11    4.72E-07    2.84E+17
    1500       -33.3       -90.8    3.96E+10    3.67E-01    1.08E+11
    2000       -33.4       -90.9    1.59E+10    2.24E+02    7.08E+07
    2500       -33.4       -90.8    7.68E+09    8.40E+03    9.14E+05
    3000       -33.3       -90.7    4.23E+09    8.08E+04    5.23E+04
______________________________________________________________________


                        PRESSURE = 10 atm N2  
______________________________________________________________________
    Temp      delta-S     delta-H      kf          kr         Keq     
     (K)    (cal/mol K)  (kcal/mol) ----(mol,cm3,s)-----   (cm3/mol)  
______________________________________________________________________
                                                                      
     300       -28.8       -88.1    5.60E+12    2.93E-50    1.91E+62
     500       -31.0       -89.0    4.38E+12    8.29E-25    5.28E+36
    1000       -32.9       -90.3    1.14E+12    4.01E-06    2.84E+17
    1500       -33.3       -90.8    3.56E+11    3.30E+00    1.08E+11
    2000       -33.4       -90.9    1.45E+11    2.05E+03    7.08E+07
    2500       -33.4       -90.8    7.13E+10    7.80E+04    9.14E+05
    3000       -33.3       -90.7    3.96E+10    7.58E+05    5.23E+04
______________________________________________________________________