THE EFFECT OF AHOKO OIL SHALE ON THE ACTIVATION ENERGY OF THE CO-PYROLYSIS WITH POLYETHYLENE

Abstract

This study explored the effect of Ahoko oil shale on the activation energy in the co- pyrolysis with polyethylene. The study of optimization of oil yield from the co-pyrolysis of oil shale and Polyethylene was investigated at different temperature based on TGA and residence time of 90 mins. DESIGN EXPERT (Version 7.0.0, Stat Ease, Inc., USA) software was applied to investigate the oil recovery process to optimize the mixture compositions for maximum oil yield and to observe the blending behavior of the two samples in relation to oil yield. Analysis of variance (ANOVA) showed the model generated was significant with a p-value <0.0001, R2 value of 0.9297, adjusted R2 of 0.9329 and predicted R2 of 0.9790. The optimum mixture composition for the oil yield was 50 % oil shale to 50 %. Dynamic pyrolysis and co-pyrolysis tests at different heating rates of 5, 10 and 15 oC/min were carried out using a thermogravimetric analyzer (TGA) to determine the kinetic parameters of the process. The obtained oils were characterized using Fourier transform infrared spectrometer (FT-IR) and Gas Chromatograph Mass Spectrometry (GCMS). The kinetics of pyrolysis and co-pyrolysis was determined via model-free iso-conversional methods, from the model, oil shale had an activation energy value of 45.19, 42.00, 44.55 and 46.32 kJ/mol with respect to Arrhenius, Flynn-wall- ozawa, Freidman and Coats-Redfen method respectively. The Polyethylene had an activation energy value of 153.14 154.64, 158.72, 155.41 kJ/mol in respect to Arrhenius, Flynn-wall-ozawa, Freidman and Coats-Redfen method respectively. The activation energy for the mixture was also calculated to be 52.95, 49.86, 51.04 and 52.33 kJ/mol with respect to Arrhenius, Flynn-wall-ozawa, Freidman and Coats-Redfen method respectively. Among the four models used for this work which used linear regression, the FWO method showed the best fit to the experimental TGA data for both oil shale, polyethylene and their mixture pyrolysis. The results showed that the activation energy of co-pyrolysis was evidently lower than that of polyethylene pyrolysis. This led to the conclusion that co-pyrolysis could be a potential method for obtaining shale oil due to the synergy between oil shale and polyethylene.