Exploring the oxidation chemistry of diisopropyl ether: Jet-stirred reactor experiments and kinetic modeling

Diisopropyl ether (DIPE) is considered as a promising gasoline additive due to the favorable blending Reid vapor pressure and the low water solubility. The DIPE oxidation chemistry was studied via oxidation experiments of a stoichiometric mixture of DIPE/O₂/Ar/Kr in a jet-stirred reactor (JSR) at atmospheric pressure over the temperature range of 525 K–900 K. About 30 intermediates and products were identified and quantified using a photoionization molecular-beam mass spectrometer. Also, a detailed kinetic model was proposed for DIPE oxidation, which showed satisfactory performances in predicting the species concentration profiles. For DIPE oxidation, the fuel consumption was observed only above 750 K, even though DIPE has two tertiary hydrogen atoms that are easy to be abstracted so that low-temperature oxidation reactivity is expected. The low oxidation reactivity at low temperature was because the formed OOQOOH radical mostly dissociated back to QOOH + O₂, instead of undergoing intramolecular isomerization which led to the low-temperature chain-branching. At higher temperature, DIPE was mainly consumed by hydrogen abstraction reactions from the carbon atoms adjacent to the oxygen atom, producing dominantly the IC₃H₇OC(CH₃)₂ fuel radical, which decomposed rapidly via C–O bond Β-scission instead of combining with O₂.