Theory-Based Mechanism for Fluoromethane Combustion I: Thermochemistry and Abstraction Reactions

A new detailed chemical kinetic mechanism is presented
for small
fluorinated hydrocarbons. Ab initio electronic structure theory is
used to provide heats of formation with subchemical accuracy. The
ANL0 method is extended to include fluorine. The resulting heats of
formation at 0 K are in excellent agreement with 36 benchmark species
in the Active Thermochemical Tables, with a mean error of μ
= −0.02 kJ/mol and a standard deviation of σ = 0.91 kJ/mol.
The thermophysical properties for 92 small-molecule H/C/O/F species
are computed. The rate coefficients for 40+ H-abstraction reactions
involving H, O, F, OH, OF, HO2, and various methyl radicals
with CH4, CH3F, CH2F2,
CHF3, CH2O, and CHFO are discussed. The computed
rate constants are in excellent agreement with the available literature.
Additionally, 30+ rate constants are provided for F abstraction, which
are several orders of magnitude smaller than H abstraction. The thermophysical
properties and rate constants are provided in a mechanism. This mechanism
is the first in a series of theory-based investigations into the thermal
destruction of per- and polyfluorinated species.