Cool flame product characterization from the low-temperature oxidation of n-dodecane

n-Dodecane is a potential diesel and jet fuel surrogate. The combustion chemistry of n-dodecane has long been a research focal point, but its long carbon-chain length makes it challenging to obtain detailed information on cool flame intermediates and products. Determining the detailed formation mechanism of combustion intermediates is important to validate possible reaction pathways, develop detailed reaction mechanisms, and improve kinetic models. Reports on its low-temperature (low-T) oxidation, including detailed speciation in the oxidation process, are scarce. In this work, low-T oxidation of n-dodecane was investigated in a jet-stirred reactor coupled with synchrotron vacuum ultraviolet photoionization mass spectrometry and gas chromatography. Experimental conditions were maintained at atmospheric pressure with an initial fuel concentration of 0.4%, equivalence ratio of 0.5, and residence time of 2 s. A large number of cool flame intermediates and products, including alkenes, dienes, aldehyde/keto compounds, olefinic aldehyde/keto compounds, diones, cyclic ethers, peroxides, acids, and alcohols/ethers, were identified and classified. Particular attention is focused on understanding these intermediates and products. Detailed structures and the most likely formation channels for these species are proposed and discussed herein. These results provide a solid database for the low-T oxidation of n-dodecane, which is important for the development of future kinetic models.