Specific kinetic triplet estimation of Tahe heavy oil oxidation reaction based on non-isothermal kinetic results

Abstract

Although the oxidation mechanisms and kinetics characteristics of heavy oils have been involved in enormous studies, little attention is paid to the specific kinetics triplet and activation energy distribution in detailed temperature ranges. In this study, the non-isothermal oxidation kinetics characteristics of the Tahe heavy oil, including kinetics triplet, activation energy distribution (E-α curve) and thermodynamic parameters under specific temperature subzones, were investigated by thermo-analysis techniques and Popescu method. And it indicated that six sequential temperature subzones were identified with different mechanism function, G(α), and rate constant, k(T). Besides, it can be seen from the E-α curve that the first obvious increasing peak was attributed to the negative temperature gradient region (NTGR) and the second mild peak corresponded to the initiation stage of the combustion process, between which positive temperature coefficient and negative temperature coefficient zones were located at the valley. Additionally the calculated thermodynamic parameters (△S*, △H*, △G*) indicated that the non-isothermal oxidation process for Tahe heavy oil is the non-spontaneous reaction and needs heat to occur under atmospheric pressure.