Isobutene oxidation and ignition: Experimental and detailed kinetic modeling study

The oxidation of isobutene has been investigated for the first lime in a je t-stirred reactor at high temperature (similar to 800-1230 K) and at 1, 5 a nd 10 atm. Molecular species concentration profiles of O-2, H-2, CO, CO2, C H2O, CH4, C2H2, C2H4, C2H6, C3H4(allene and propyne), C3H6, acetone, acrole in, 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 ignitio n of isobutene-oxygen-argon mixtures in a shock-tube were modeled using a d etailed 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 g as blends in the same conditions, is able to predict experimental results o btained in our high-pressure jet stirred reactor and the ignition delays me asured 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.