Reassessment of the High-Temperature Oxidation of Di Ethyl Ether through Ab Initio Calculations

Recent
investigations of diethyl ether (DEE) high-temperature pyrolysis
and fuel-rich oxidation have highlighted the failure of existing kinetic
models to describe experimental CO production. The DEE high-temperature
pyrolysis and oxidation chemistry is thus investigated through ab
initio calculations. Geometries, frequencies, and hindered-rotor potentials
of reactants, products, and transition states of key reactions (fuel
decomposition radical decomposition and H-abstraction reactions) are
calculated with the B2PLYP-D3/def2-TZVPD method, whereas final energies
are refined using CCSD(T)/aug-cc-pV(D,T)Z. Temperature- and pressure-dependent
rate constants are then derived from either canonical transition state
theory (CTST) or ME/RRKM analysis with the inclusion of tunneling
effect and hindered-rotor corrections and compared to experimental
measurements when available as well as to previously suggested values.
This new information is then merged with a C0–C3 core chemistry model and a low-temperature chemistry DEE
subset from the literature to propose a new kinetic model for the
combustion of DEE. This model is tested successfully against a large
database related to the high-temperature oxidation and pyrolysis chemistry
of DEE, including ignition delay times, shock tube speciation data,
time-resolved CO profiles, laminar flame speeds, flame structures,
and jet-stirred reactor data.