Oxidation of isobutane and isobutene reaction pathways and detailed mechanism

A reaction mechanism consisting of 248 elementary reactions and 138 species has been developed to model experimental systems - decomposition of 2,2,3,3 tetramethylbutane in the presence of oxygen and oxidation of isobutene. This elementary reaction mechanism based on two important reaction systems: tert-butyl radical with O2 and allylic isobutenyl radical with O2, plus their subsystems, such as isobutene + HO2, isobutene + OH and allylic isobuteny1hydroxy + O2. Thermochernical kinetic parameters are developed for each elementary reaction and a chemical activation kinetic analysis using quantum RiceRamsperger-Kassel (QRRK) theory for k(E) and modified strong collision analysis for falloff is used to calculate Vs as function of pressure and temperature. All reactions in the mechanism incorporate reverse reaction rates calculated from thermodynamic parameters and microscopic reversibility. Results show that several important equilibria are achieved with product formation effected by slow (bleed) reaction out of the equilibrium system. In tert-butyl radical with O2 system it shows a near 200 to 1 dominance of the isobutene + HO2 channel over formation of the 2,2-dimethyloxirane + OH at 60 torr. Rate constants and detailed reaction paths for formation of important products: acetone, methacrolein, and epoxides, and formation of five-member and the four-member cyclic intermediates are determined in allylic isobutenyl radical with O2 system. Predictions are in good agreement with experimental data