Thermogravimetric and Kinetic Analysis on Pyrolysis and Combustion of Oil Shale Under Different Oxygen Concentration Atmosphere

The kinetics of combustion of oil shale by different oxygen contents(11,21,42 and 63% Vol.) has been investigated by thermogravimetric analyzer (TGA) at three different heating rates (10,30 and 50°C/min). The Activation energy E of oil shale thermal decomposition under different oxygen concentrations were determined by iso-conversional method (Kissinger-Akahira-Sunose (KAS) method and Flynn–Wall-Ozawa (FWO) method). The data obtained from TG was used to calculate the Activation energy and discuss the influence of oxygen concentration on kinetic parameters. According to the TG results, the combustion process of oil shale could be divided into three stages, the evaporation of water, the combustion of the decomposition of organic matter and combustion of semicoke. The TG revealed that the oxygen content in atmosphere does not affect the evaporation stage but influence the combustion stage. The results show that the average activation energies were 134.85, 163.41, 211.19 and 242.32 KJ/mol. Activation energy using KAS method were 136.50, 167.37, 216.49 and 225.38 KJ/mol, whereas the FWO method at different oxygen contents were: 11,21,42, 63 vol%,respectively. The results of kinetic calculation revealed that the activation energy values of the combustion increase with increase of oxygen content.