Comparative study on thermal cracking of Athabasca bitumen Evaluation of the activation energy and prediction of the isothermal conversion by different isoconversional methods

摘要

In this study, three commonly used isoconversional methods, namely: Ozawa–Flynn–Wall (OFW), Kissinger–Akahira–Sunose (KAS), and the advanced non-linear integral method of Vyazovkin (NLN) were employed for the first time for calculating the activation energy for thermal cracking of Athabasca bitumen under inert conditions. Thermal cracking of Athabasca bitumen was carried out at nonisothermal conditions at different heating rates under nitrogen atmosphere using thermogravimetic analyzer (TG). One isothermal TG experiment was conducted for model prediction. Differences in the values of activation energy determined from the three methods selected have been demonstrated. These differences were mainly attributed to the approximations used for the temperature integral employed in the integral methods.Nonetheless, all the methods tested in this study provided satisfactory isothermal predictions. The study showed that, among the three methods tested, the NLN method provided more accurate results. This is because NLN is approximation free and uses small time segments for the temperature integral.