Towards a deeper understanding of the oxidation of isobutane to tert-butyl hydroperoxide in the liquid phase by an extended kinetic model. Initiation by di-tert-butyl peroxide

• Extended kinetic model of the partial oxidation of isobutane (p.o.i.). • Model based on elementary rate constants of p.o.i. • Model includes both initiation and autocatalysis of p.o.i. • Model distinguishes heterogeneous and homogeneous p.o.i. reactions. • Model structure validated using experimental data from the literature. To date, the liquid phase oxidation of isobutane has not been comprehensively described in the literature, since the established kinetic models include either the effect of the initiator or the autocatalytic nature of the oxidation of isobutane, but not both. To overcome this deficiency, an extended kinetic model was developed and validated using experimental data from the literature. It enabled for the first time the distinction of three different processes: the oxidation of isobutane, the heterogeneous, unimolecular decomposition of tert -butyl hydroperoxide on the reactor wall and the homogeneous decomposition reactions of TBHP in solution. The rate constant of the heterogeneous unimolecular decomposition of TBHP on the wall surface of an untreated stainless-steel reactor, was found to be two to five times higher than that which was observed in a passivated steel reactor. However, similar values for the respective parameters describing the first-order decomposition of TBHP and the oxidation of isobutane were obtained in both reactors. In the non-passivated stainless-steel reactor, the second order decomposition of TBHP was absent. The results were compared with published data.