Computer modeling of formation of soot precursors in the oxidation of methane

Abstract

A previously developed method was extended for computer modeling of chemical processes involving large number of species. Improvements introduced for the combinatorial generation of stoichiometrically possible reaction steps include hierarchical structuring of the chemical system under study, replacing invariant atomic groups by symbols, as well as the combined application of two complexity constraints for the reduction of the set of reactions. Modeling revealed that while in the oxidation of methane the formation of ethynyl benzene (phenylacetylene), 1‐naphtyl radical, diethynyl benzene and ethynyl naphtalene by acetylene addition to the precursor radicals can be accepted to proceed in a single elementary step, this is not valid for anthracyl radical. Formation of acenaphtylene, 12‐biphenyl radical, 3‐phenantryl radical, phenantrene, and pyrene needs further investigation in this respect. Furthermore, formation of benzene, phenyl, and biphenyl by recombination of propargyl or substituted propargyl radicals in a single elementary reaction was not supported by modeling. Results suggest the possibility of not yet identified intermediates participating in these processes.