Experimental and kinetic modeling study of 2-methyltetrahydrofuran oxidation under engine-relevant conditions

The oxidation of 2-methyltetrahydrofuran (2-MTHF) has been experimentally studied in a rapid compression machine. The ignition delays of stoichiometric 2-MTHF/O2/inert mixtures were measured for a wide range of conditions: Top dead center pressure ranging from 0.3 to 2.1 MPa and core gas temperatures between 640 K and 900 K. Two-stage ignition is observed for temperatures between 685 K and 790 K, leading to a deviation from Arrhenius behavior of the evolution of ignition delays with temperature. Sampling of the reacting mixture was performed for different times between the top dead center and the ignition. Stable reaction intermediates were separated by gas chromatography, identified by mass spectrometry and quantified with a flame ionization detector. More than 20 species were identified and used to identify major reaction pathways. Among species of importance, 2-methyl-dihydrofurans, 2-methylfuran, methyldihydrofuranones, 1-cyclopropanylethanone, 3-penten-2-one and methylvinylketone were detected. Mole fraction profiles were obtained and used alongside first stage and total ignition delays to validate a detailed kinetic model for the oxidation of 2-MTHF. The resulting model takes in account 507 species involved in 2425 reactions. The validity of this model was extended to the high temperature range using existing ignition delays and low pressure laminar flame speciation data.