Thermal decomposition of indene. Experimental results and kinetic modeling

Abstract

The thermal decomposition of indene was studied behind reflected shock waves in a pressurized driver single-pulse shock tube over the temperature range 1150–1900 K and densities of ≈3×10⁻⁵ mol/cm³. GC analyses of post-shock mixtures revealed the presence of the following decomposition products, given in order of increasing molecular weight: CH₄, C₂H₂, CH₂=C=CH₂, CH₃C≡CH, C₄H₂, C₆H₆, C₆H₅−CH₃, C₆H₅−C≡CH, and also naphthalene and its structural isomer, probably 1-methylene-1H-indene. Small or trace quantities of C₂H₄, C₄H₄, C₅H₆, C₅H₅−C≡CH, and C₆H₄ were also found in the postshock mixtures. A kinetic scheme based on cyclopentadiene decomposition pathway alone cannot account for the observed product distribution. It can be accounted for if H-atom attachment to the π bond in the five-membered ring followed by consecutive decomposition of the formed indanyl radical is assumed in addition to the indenyl channel. A reaction scheme with the two pathways containing 50 species and 74 elementary reactions reproduces very well the experimental product distribution. In this paper, we show the reaction scheme, the results of computer simulation, and sensitivity analysis. Differences and similarities in the reaction patterns of cyclopentadiene and indence are discussed.