Jet-Stirred Reactor Study of Low-Temperature Neopentane Oxidation: A Combined Theoretical, Chromatographic, Mass Spectrometric, and PEPICO Analysis

The oxidation of neopentane was studied in jet-stirred reactors at atmospheric pressure over a temperature range 500-850 K and phi = 0.5. The products were analyzed with chromatographic, mass spectrometric, and photoelectron spectroscopic setups complemented with theoretical calculations. This combination provides a comparison of photo-ionization mass spectrometry and gas chromatography for the quantification of mole fractions and highlights the relevant differences between them, while mass-tagged photoelectron spectroscopy sheds light onto the isomeric distribution. The new data and corresponding analyses are expected to provide valuable guidance for an extension of the kinetic model and the choice of experimental methods. The main first and second O-2-addition products were observed in agreement with the literature (e.g., 3,3-dimethyloxetane, acetone, isobutene, and gamma-ketohydroperoxide). The simulated mole fractions of the products using a literature kinetic model were compared to the experimental results. Even though the kinetic model has been validated previously, significant discrepancies between the measured and simulated mole fractions of 2-methylpropanal and methacrolein, two fuel-specific low-temperature oxidation products, were found. Furthermore, some experimentally observed species related to gamma-ketohydroperoxide decomposition were not predicted indicating that the model is incomplete. The detection of 2-methylpropanal and formic acid highlighted the importance of the Korcek-type pathway.