Pyrolysis of automobile tyre waste. Influence of operating variables and kinetics study

Abstract

Shredded automobile tyres were pyrolysed in an N 2 atmosphere. The compositions and properties of the different fractions were determined over a range of temperatures (350–700°C) and heating rates (5–20 K min −1). Char yields fell and gas yields rose with increasing temperature. The oil fraction yield passed through a maximum at 550–575°C. The decline at higher temperatures was likely due to strong cracking increasing the gas yield. Increasing the heating rate led to similar results to those obtained with temperature. Production from the tyre feedstock was approximately 37–40% char, ∼55% oil and 4–11% gas, with medium higher heating values of 28 MJ kg −1, 39.7 MJ kg −1 and 34 MJ N −1 m −3, respectively. The char had a high fixed-carbon content and could be used to manufacture category-A briquettes. Aliphatic and aromatic hydrocarbons and hydroxyl compounds were the major components of the oil. The gases were identified as H 2, CO, CH 4, CO 2, C 2H 4 and C 2H 6. We studied the kinetics of the thermal decomposition of the feedstock using isothermal and non-isothermal thermogravimetric methods at different temperatures (400–600°C) and heating rates (5–50 K min −1). The results indicated that the isothermal pyrolysis process consisted of one stage and the non-isothermal three stages.