Thermal cracking and combustion kinetics of asphaltenes derived from Fosterton oil

Thermal behavior of crude oil (Fosterton) asphaltenes mixed with reservoir sand was investigated using thermogravimetric analysis (TGA), in nitrogen and air atmospheres for different heating rates up to 800 degrees C. In this Study, four sets of TGA runs were performed to examine the thermal behavior of Fosterton asphaltenes and the coke derived from the asphaltenes. The parameters studied were heating rate (10. 15 and 20 degrees C min(-1)) and the type of purge gas (N-2 and air) employed for the process of thermal degradation of asphaltenes. Distributed activation energy model (DAEM) has been applied to study the asphaltene pyrolysis kinetics. It was observed that the activation energy was distributed from 46.16 to 72.17 kJ/mol, for the conversion range of 0.1 to 0.4. The general model for nth order reaction was used to obtain the kinetic parameters of coke oxidation reaction from the TGA data. From the model. the calculated activation energy, E, was 93.46 kJ/mol and the pre-exponential factor was 9.59 x 10(5) min(-1) for the coke combustion. The apparent order of combustion reaction gradually increased from 0.7 to 0.8 for different temperatures. (C) 2009 Elsevier B.V. All rights reserved.