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

Recent\ninvestigations of diethyl ether (DEE) high-temperature pyrolysis\nand fuel-rich oxidation have highlighted the failure of existing kinetic\nmodels to describe experimental CO production. The DEE high-temperature\npyrolysis and oxidation chemistry is thus investigated through ab\ninitio calculations. Geometries, frequencies, and hindered-rotor potentials\nof reactants, products, and transition states of key reactions (fuel\ndecomposition radical decomposition and H-abstraction reactions) are\ncalculated with the B2PLYP-D3/def2-TZVPD method, whereas final energies\nare refined using CCSD(T)/aug-cc-pV(D,T)Z. Temperature- and pressure-dependent\nrate constants are then derived from either canonical transition state\ntheory (CTST) or ME/RRKM analysis with the inclusion of tunneling\neffect and hindered-rotor corrections and compared to experimental\nmeasurements when available as well as to previously suggested values.\nThis new information is then merged with a C<sub>0</sub>–C<sub>3</sub> core chemistry model and a low-temperature chemistry DEE\nsubset from the literature to propose a new kinetic model for the\ncombustion of DEE. This model is tested successfully against a large\ndatabase related to the high-temperature oxidation and pyrolysis chemistry\nof DEE, including ignition delay times, shock tube speciation data,\ntime-resolved CO profiles, laminar flame speeds, flame structures,\nand jet-stirred reactor data.