Utilizing the Decomposition of Onelga Oil Shale to Fix Kinetics Parameter and Heat Energy for Pyrolyser-Reactor

Abstract

Oil shale in Nigeria is an emerging resource and the heat energy required to refine the kerogen content is a stiff challenge. The aim of this work is to develop the kinetics of the decomposition of the newly found oil shale in order to provide a viable process when it is explored. A dataset of thermo gravimetric analysis (TGA) of the Onelga oil shale is provided and two distinct kinetic models have been employed. The experimental techniques involve the decomposition reaction process prior to thermogravimetry/differential thermogravimetric analysis (TGA/DTGA) for non-isothermal heating conditions. The minerals in oil shale have been removed by treating the sample with hydrochloric acid. On the other hand, the pyrolysis experiments have been performed by increasing the heating temperature up to 900 °C at heating rate of 10 °C/min in an inert atmosphere of nitrogen gas. The plot of the concentration with respect to time has provided the decomposition of oil shale and yield of oil and gas. For the TGA, the second stage is significant because the organic matter decomposes and this the hydrocarbon matter decomposes within the range of 220-580 °C. At high temperatures of 750-900 °C, the loss due to decomposition of mineral matter has occurred and the bitumen has charred completely. Direct Arrhenius and integral methods have been suitable to determine the activation energies of the pyrolysis reaction. The activation energies for the organic matter of Onelga raw and acid treated Onelga oilshale samples have been 203.00–291.92 and 156.94–238.95 kJ/mol respectively. Thus, the removal of mineral matter alters the kinetic parameter of the process of oil volatility from the organic matter. The deviations in kinetic parameter between the model and the preliminary experimental data have been negligible and this validates the models obtained.