Pyrolysis kinetics of a Wangqing oil shale using thermogravimetric analysis

Abstract

A thermogravimetric analyzer was used to study the pyrolysis characteristics of an oil shale at different heating rates. Friedman, Flynn–wall–Ozawa (FWO), and distributed activation energy model (DAEM) methods were used to calculate the kinetic parameters of low-temperature pyrolysis of oil shale. The results show that as the heating rate increases, (a) the initial pyrolysis temperature, peak temperature, and final pyrolysis temperature of oil shale shift toward the high-temperature region, (b) the range of devolatilization temperature increases, and (c) the peak value of oil shale weight loss increases. The apparent activation energies calculated using the FWO and Friedman methods change with the conversion rate, and the average activation energies are 233.71 and 234.61 kJ/mol, respectively. Kinetic parameters obtained from the DAEM calculation of low-temperature pyrolysis of oil shale have energy compensation effects. By combining F-test and quantitative criterion test, it was found that the logistic DAEM model is suitable for solving oil shale kinetic parameters. The activation energy of low-temperature pyrolysis of oil shale is 238.67 kJ/mol, and the reaction order n is 1.