Energy and chemical recovery of pyrolysis oils from used tires ; Valorisation énergétique et chimique des huiles de pyrolyse des pneus usagés

The worldwide generation of used tires is estimated at over one billion each year. They are a bulky and environmentally harmful solid waste that takes centuries to biodegrade. Currently, the disposal and handling of this waste are major concerns. Thermal treatment of used tires is preferred to other management methods. It promotes its transformation into energy and valuable chemicals. The objective of this work is the recovery of used tires by pyrolysis. The research carried out in this thesis focused on the pyrolysis oils in order to recover chemical compounds with high market values and to produce alternative fuels. The operating parameters influencing the occurrence of secondary reactions, namely the heating rate, the inert gas flow rate, and the reactor free volume were studied by thermogravimetric analysis (TGA) and then on a fixed bed batch reactor. It was concluded that the pyrolysis takes place in a thermal range of 200 to 500 °C with a yield of about 60 % in volatile matter.The absence of carrier gas throughout the pyrolysis process has a noticeable effect on the recovered oil composition. The most abundant chemical compound was d-limonene with about 18 % (by mass). This last was competed by p-cymene and BTXs. The conversion reactions of d-limonene to p-cymene and to BTXs have been identified. The continuous sweeping with the inert gas dramatically decreased the extent of the primary volatiles secondary cracking. It promoted the retention of d-limonene to the detriment of p-cymene and BTXs. The total yield of d-limonene was about 22 %. The decrease in the free volume of the reactor led to a reduction in the volatiles residence time, thus preventing the emergence of these secondary reactions. At the end of the thesis, an original thermodynamic model of pyrolysis oil was created using the Simulis Thermodynamics©. Two valuation strategies were subsequently simulated using the ProSimPlus© software. Both configurations proved the feasibility of pyrolytic oil fractionating into an alternative fuel similar to ...