Exploring thermokinetic behaviour of Jurassic coal during pyrolysis and oxidation

Abstract

The thermokinetics and gaseous products of Jurassic coals collected from northern Shaanxi, China at four different heating rates were determined via thermogravimetry-Fourier transform infrared spectroscopy experiments. The results showed that the trends of thermogravimetric pyrolysis and oxidation curves were divided into three stages and five stages, respectively, and presented the same variations. As the heating rate increased, their curves moved the high temperature. In addition, the characteristic temperatures indicated that the coal samples had a relatively significant spontaneous combustion tendency. In the stage of water evaporation and gas desorption, the rates of formation of CO and CO2 went up promptly, and gaseous water produced during the oxidation reaction began to increase, but its generation rate was lower than that in the stage of oxygen absorption and mass increase. The apparent activation energy (Ea) showed a characteristic jump with increasing temperature, and the optimal mechanism function was chosen by integration and differentiation. Moreover, the relationship between Ea and lnA was linear, which indicated that there was a kinetic compensation effect.