Isobutene oxidation and ignition: Experimental and detailed kinetic modeling study

The oxidation of isobutene has been investigated for the first lime in a jet-stirred reactor at high temperature (similar to 800-1230 K) and at 1, 5 and 10 atm. Molecular species concentration profiles of O-2, H-2, CO, CO2, CH2O, CH4, C2H2, C2H4, C2H6, C3H4(allene and propyne), C3H6, acetone, acrolein, methacrolein, 1-C4H8, i-C4H8, 1,3-C4H6, 1-butyne, isoprene, 2-methyl-1-butene, 2-methyt-2-butene, and benzene were obtained by probe sampling and GC analysis. The oxidation of isobutene in these conditions and the ignition of isobutene-oxygen-argon mixtures in a shock-tube were modeled using a detailed kinetic reaction mechanism (110 species and 743 reactions, most of them reversible). The proposed mechanism, also validated for the oxidation of CH4, C2H2, C2H4, C2H6, C3H6, acetaldehyde, ethylene oxide, and natural gas blends in the same conditions, is able to predict experimental results obtained in our high-pressure jet stirred reactor and the ignition delays measured behind a reflected shock wave. Two routes to benzene formation have been delineated: (a) the addition of propargyl radicals to allene, and (b) the recombination of propargyl radicals. Sensitivity analyses and reaction path analyses are used to interpret the present results.