Introduction In recent years, the plastic materials have became an important part of solid urban waste, with plastics from containers and packaging representing around 60% of this type of waste. The composition of this residue is mainly polyolefins (high and low density polyethyl- ene, polypropylene and polystyrene), accounting for around 70% of the total plastic waste [1]. As only a small amount of waste plastic is recycled and most plastics are not biodegradable, these strong uses have led to the generation of an increased amount of plastic waste. Therefore, technical have to be implemented to reduce plastic wastes negative impact on the environ- ment. Landfilling or incineration of plastic waste are not the right solutions, because the former has the danger of leaching and soil impregnation of its degra- dation products and the latter produce several pollut- ants (nitrous and sulphur oxides, dusts, dioxins and other toxins) that have a highly negative impact on the environment. Both processes do not allow the re- covery of the organic content of plastic waste, which should be part of the organic life-cycle. The search for new alternative fuels, together with the necessity of searching new technology to re- duce the negative environment impact of plastic wastes, has led to the idea of studying co-pyrolysis of plastic wastes and oil shale. The plastics consist of hydrocarbons-type macromolecules with a significant intrinsic energy and a very high calorific value [2, 3]. These materials are rich in hydrogen in comparison with coal [4, 5–9] and oil shale [10–15]. Oil shale, on the other hand, is consid- ered to be the substitute for oil as a natural source of en- ergy. However, the extraction of oil from oil shale is rel- atively expensive and uneconomical. Therefore, re- search for processes of oil shale utilization as a source of energy gains a high level of importance [16–19]. The three oil shale deposits in Morocco (Timahdit, Tanger and Tarfaya) represent about 15% of known oil shale resources in the world [20]. Extensive exploration and processing research has been conducted over the past decades [21]. These shale oil resources have been estimated to be 50 billion barrels [20]. Timahdit and Tarfaya oil shale deposits are the biggest and the most explored deposits in Morocco to have the potential to yield 17 and 23 billion barrels respectively. The co-treatment of oil shale mixed with plastic wastes into useful energetic products or into valuable chemicals can be achieved in a thermochemical pro- cesses [10–15]. Pyrolysis has received special atten- tion since it produces solid, liquid and gas products. With these purposes, the knowledge of the kinetics of degradation is necessary for the design of specific re- actors. Thermogravimetric behaviour has been proved to be a very powerful tool for materials char- 1388–6150/$20.00 Akadémiai Kiadó, Budapest, Hungary © 2007 Akadémiai Kiadó, Budapest Springer, Dordrecht, The Netherlands Journal of Thermal Analysis and Calorimetry, Vol. 89 (2007) 1, 203–209 PYROLYSIS KINETICS OF POLYPROPYLENE Morocco oil shale and their mixture A. Aboulkas 1 , K. El Harfi 1* , A. El Bouadili 2 , M. Ben Chanâa 1 and A. Mokhlisse 1 1 Laboratoire de Chimie Physique, Département de Chimie, Faculté des Sciences Semlalia, Université Caddi Ayyad, BP 2390, 40001 Marrakech, Maroc 2 Laboratoire de Chimie Organique et Analytique, Departément de Chimie, Faculté des Sciences et Techniques de Béni-Mellal, Université Caddi Ayyad, BP 523, 23000 Béni-Mellal, Maroc The pyrolysis of oil shale and plastic wastes is being presently considered as an alternative means of partial substitution of fossil fu- els to generate the necessary energy to supply the increasing energy demand and as well as new technology to reduce the negative environment of plastic wastes. However, Knowledge of pyrolysis kinetics is of great imponrtance for the design and simulation of the reactor and in order to establish the optimum process conditions. In this study, the thermal decomposition of polypropylene, oil shale and their mixture was studied by TG under a nitrogen at- mosphere. Experiments were carried out for various heating rates (2, 10, 20, 50 K min –1 ) in the temperature range 300–1273 K. The values of the obtained activation energies are 207 kJ mol –1 for polyethylene, 57 kJ mol –1 for the organic matter contained in the oil shale and 174 kJ mol –1 for the mixture. The results indicate that the decomposition of these materials depends on the heating rate, and that polypropylene acts as catalyst in the degradation of the oil shale in the mixture. Keywords: dynamic thermogravimetry, kinetics, oil shale, polypropylene, pyrolysis * Author for correspondence: elharfi@ucam.ac.ma