Saito, K., Kakumoto, T., Nakanishi, Y., and Imamura, A. (1985)
Thermal Decomposition of Formaldehyde at High Temperatures
J. Phys. Chem. 1985, 89, 3109.
Abstract
The thermal decomposition of formaldehyde was investigated behind reflected shock
waves by monitoring time-dependent CH2O and CO concentrations by IR emission and
H-atom concentration by the ARAS method. From the IR emission experiment, it was
found that the CH2O decay and the CO formation rates were the same and showed a
strong dependence on the reactant mole fraction. An Arrhenius expression for the
second-order rate constant of CH2O + Ar -> CHO + H + Ar was obtained as k=
10^15.50exp(-75.0 kcal/mol /RT) cm3/mol s over the temperature range 2200-2650 K.
Rate constants determined from the rate of H-atom production agreed well with
this expression. The alternative channel CH2O + Ar -> CO + H2 + Ar appeared to
have a smaller rate under the experimental conditions studied. Relative rates of
the competing channels are discussed on the basis of recent ab initio
calculations of their threshold energies.
REACTION RATE COEFFICIENTS SUGGESTED IN THIS WORK:
GRI-Mech
Number
('-' sign
means
reverse) |
Reaction |
Rate Coefficient
A T^n exp(-E/RT) |
Temperature
Range
(K) |
A
(mol,cm3,s) |
n
(T in K) |
E
(cal/mol) |
| -54* |
CH2O + M -> H + HCO + M |
3.16E+15 |
|
75000 |
2200-2650 |
| 58 |
H + CH2O -> HCO + H2 |
9.12E+13 |
|
7900 |
2200-2650 |
* M = Ar