Flow reactor oxidation study of oxymethylene ether (OME1–3): Insights from molecular-beam mass spectrometry and kinetic modeling at elevated pressure

• New laminar plug-flow reactor for elevated pressures coupled to an EI-MBMS system. • First quantitative flow reactor oxidation data of OME 2 and OME 3 at elevated pressure. • OME 1 has only low reactivity in the LTC regime at absolute pressure of 5 bar. • Both larger OMEs have higher reactivity in the LTC regime and show an NTC behavior. • Kinetic modeling by three comprehensive OME mechanisms supports experimental findings. This study investigates the oxidation of three oxymethylene ethers (OME 1–3 ) in a new elevated-pressure laminar plug-flow reactor, utilizing electron-ionization molecular-beam mass spectrometry. Experiments were conducted at an absolute pressure of 5 bar to mimic conditions more relevant to combustion systems but still allowing for the exploration of reaction kinetics and pathways in a controlled environment. The experimental work is supported by kinetic modeling using our in-house DLR Concise mechanism to gain deeper insights into OME 1-3 combustion chemistry and highlight the controlling pathways. Kinetic modeling with two additional literature mechanisms was also employed to complement the findings. The measurements at constant carbon flow and similar conditions enable a systematic analogy among the three studied OMEs. The results reveal preferred formation of small C 1 –C 2 hydrocarbons and oxygenates such as formaldehyde and methyl formate as combustion intermediates. Formation of methanol and formic acid was also observed during oxidation of all three OMEs, but the latter in significantly higher concentrations for both longer-chain OMEs. OME 1 shows only low reactivity in the low-temperature chemistry (LTC) regime, while the two larger OMEs have a higher reactivity in the LTC regime and also show a negative temperature coefficient behavior at the studied conditions. In line with previous reactor studies at atmospheric pressure, the reactivity of OME 2 and OME 3 is also similar at 5 bar, but is clearly distinguishable from OME 1 . This work not only enhances our understanding of the fundamental chemistry underlying the oxidation mechanisms of OMEs, but also underscores their potential as cleaner fuel alternatives.