Kinetics of Thermal Decomposition of Tar in the Presence of Air and Nitrogen Gas

Thermogravimetric analysis (TGA) provides useful information, which can be used in thermal processing and conversion kinetic modeling of materials, including hydrocarbons. In the present study, a series of TGA experiments were conducted in the presence of air (combustion) and under inert conditions (pyrolysis) using nitrogen gas with the focus of obtaining quantitative information to compare thermal decomposition characteristics of the two processes. The analysis was performed at different gas injection rates (10-50 mL/min) and heating rates (10-30 °C/min) under non-isothermal conditions from 30 to 600 °C. It was observed that the gas injection rates did not have significant impact on the thermal decomposition of the tar sample. However, increasing the heating rate shifted the peak temperatures of the reactions to higher temperatures. In addition, the combustion process generally has a higher conversion and peak rate of conversion than the pyrolysis process. Moreover, the activation energy, E_a (kJ mol^-1), obtained for the combustion process was observed to be higher than those of the pyrolysis.