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Theoretical Study of the Thermal Decomposition of the 5-Methyl-2-furanylmethyl Radical
journal contribution
posted on 2012-06-28, 00:00 authored by Baptiste Sirjean, René FournetThe thermal decomposition of the 5-methyl-2-furanylmethyl
radical
(R1), the most important primary radical formed during
the combustion and thermal decomposition of 2,5-dimethylfuran (a promising
next-generation biofuel), was studied using CBS-QB3 calculations and
master equation (ME)/RRKM modeling. Because very little information
is available in the literature, the detailed potential energy surface
(PES) was investigated thoroughly. Only the main pathways, having
a kinetic influence on the decomposition of R1, were retained
in the final ME/RRKM model. Among all the channels studied, the ring-opening
of the 5-methyl-2-furanylmethyl radical, followed by ring enlargement
to form cyclohexadienone molecules is predicted to be the easiest
decomposition channel of R1. The C6 cyclic species
formed can undergo unimolecular reactions to yield phenol and to a
lesser extent cyclopentadiene and CO. Our calculations predict that
these species are important products formed during the pyrolysis of
2,5-dimethylfuran (DMF). Other channels involved in the decomposition
of R1 lead directly to the formation of linear and cyclic
unsaturated C5 species and constitute an additional source
of cyclopentadiene and CO. High-pressure limit rate constants were
computed as well as thermochemical properties for important species.
ME/RRKM analysis was performed to probe the influence of pressure
on the rate coefficients and pressure dependent rate coefficients
were proposed for pressures and temperatures ranging, respectively,
from 10–2 bar to 10 bar and 1000 to 2000 K.