Experimental and kinetic modeling study of n-hexane oxidation. Detection of complex low-temperature products using high-resolution mass spectrometry

This study concerns the oxidation of n-hexane. It was conducted in continuous flow fused-silica jet-stirred reactor (JSR) at 10 atm and an equivalence ratio 0.5. n-Hexane initial concentrations were (i) 2500 ppm with a mean residence time 1.5 s (ii) 1000 0.7 s; we operated cool-flame regime for temperatures ranging from 540 to 720 K 530 800 K, respectively. Products analyzed quantified gas phase using chromatography (with flame ionization, thermal conductivity, quadrupole mass spectrometry) Fourier transform infrared spectrometry. low-temperature sampled JSR trapped acetonitrile characterization Orbitrap Q-Exactive®. Flow injection analyses (FIA) ultra-high pressure liquid (UHPLC) coupled atmospheric chemical ionization (APCI +/- modes)- high resolution spectrometry (HRMS) used characterize hydroperoxides (C6H14O2), keto-hydroperoxides (C6H12O3, C3H6O3, C4H8O3, C5H10O3), cyclic ethers (C6H12O), carboxylic acids (C2 C6), ketones (C3 diones (C6H10O2), unsaturated (C6H10O C6H8O), (C6H8O2), highly oxygenated molecules (C6H12O4-8) produced by addition three four oxygen on fuel's radicals. To confirm presence hydroxyl or hydroperoxyl groups products H/D exchange D2O. 2,4-Dinitrophenylhydrazine (2,4-DNPH) derivatization different carbonyls which can be formed during low temperature An available kinetic reaction mechanism including 3rd O2 radicals simulate formation presently detected (KHP) (HOMs).