The oxidation of 1,3-butadiene: Experimental results and kinetic modeling

The oxidation of 1,3-butadiene has been investigated in a jet-stirred react or at high temperature (similar to 750-1250 K), variable pressure (1 and 10 atm) and variable equivalence ratio (0.25 less than or equal to phi less t han or equal to 2). Molecular species concentration profiles of O-2, H-2, C O, CO2, CH2O, CH4, C2H2, C2H4, C2H6, C3H4 (allene and propyne), C3H6, acrol ein, 1-C4H8, 2-C4H8 (cis and trans), 1,3-C4H6, vinylacetylene, cyclopentadi ene, and benzene were obtained by probe sampling and GC analysis. The oxida tion of 1,3-butadiene in these conditions was modeled using a detailed kine tic reaction mechanism (91 species and 666 reactions, most of them reversib le). The proposed mechanism, also validated for the oxidation of simpler hy drocarbons and natural gas blends in the same conditions, is able to reason ably well-predict the experimental results obtained in this study. Sensitiv ity analyses and reaction path analyses, based on species net rate of react ion, are used to interpret the present results. The routes to benzene forma tion have been delineated: At low fuel conversion and low temperature, benz ene is mostly formed through the addition of vinyl radical to 1,3-butadiene , yielding 1,3-cyclohexadiene, followed by two channels: (a) elimination of molecular hydrogen to yield benzene and (b) decomposition of 1,3-cyclohexa diene yielding cyclohexadienyl followed by its decomposition into benzene a nd H atom; at high fuel conversion and higher temperature, (c) the recombin ation of propargyl radicals and (d) the addition of vinyl to vinylacetylene increasingly yield to benzene formation.