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

Shredded automobile tyres were pyrolysed in an N-2, atmosphere. The composi tions and properties of the different fractions were determined over a rang e of temperatures (350-700 degreesC) and heating rates (5-20 K min(-1)). Ch ar yields fell and gas yields rose with increasing temperature. The oil fra ction yield passed through a maximum at 550-575 degreesC. The decline at hi gher temperatures was likely due to strong cracking increasing the gas yiel d. Increasing the heating rate led to similar results to those obtained wit h temperature. Production from the tyre feedstock was approximately 37-40% char, similar to 55% oil and 4-11% gas, with medium higher heating values o f 28 MJ kg(-1), 39.7 MJ kg(-1) and 34 MJ N-1 (-3), respectively. The char h ad a high fixed-carbon content and could be used to m(-3) manufacture categ ory-A briquettes. Aliphatic and aromatic hydrocarbons and hydroxyl compound s were the major components of the oil. The gases were identified as H-2, C O, CH4, CO2, C2H4 and C2H6. We studied the kinetics of the thermal decompos ition of the feedstock using isothermal and non-isothermal thermogravimetri c methods at different temperatures (400-600 degreesC) 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. (C) 2001 Elsev ier Science B.V. All rights reserved.