Kinetic analysis of pyrolysis and thermal oxidation of bitumen

Abstract

In this study, thermogravimetry (TG) coupled with differential thermal analysis (DTA) was performed to examine the thermal behavior of a straight-run distillation bitumen utilized in a variety of applications, including the conditioning of nuclear waste. The non-isothermal characterization of this bitumen was carried out from 30 to 900 °C with heating rates of 1, 2, 5, 10 and 25 °C/min, in nitrogen and air atmospheres. TG and DTA results showed that under nitrogen atmosphere, pure bitumen shows a single thermal event, which is attributed to its pyrolysis. While under air, it undergoes two exothermic low temperature oxidation stages, one endothermic fuel deposition stage, and one exothermic high temperature oxidation. Kinetic parameters were determined using Kissinger, Friedman and advanced non-linear (NLN) methods to assess activation energy for each event, from the non-isothermal experimental data. Good agreement between kinetic modeling was found for bitumen under nitrogen and air.