Pyrolysis of scrap tyres

Cross-section samples (2-3 cin wide), representative of a whole car tyre, h ave been pyrolysed under nitrogen in a 3.5 dm(3) autoclave at 300 degreesC, 400 degreesC, 500 degreesC, 600 degreesC and 700 degreesC. The whole solid , liquid and gaseous products generated during each pyrolysis were collecte d and characterised. No significant influence of temperature on the amount and characteristics of pyrolysis products was observed over 500 degreesC. T yre-pyrolysis liquids are a complex mixture of C-5-C-20 organic compounds, with a great proportion of aromatics. They have high gross calorific values , GCV (similar to 42 MJ kg(-1)) and N and S contents (0.4% and 1.2%, respec tively) within those specified for certain heating fuels, About 30 wt.% of such liquids is an easily distillable fraction with boiling points (70-210 degreesC) in the range of commercial petrol, and about 60 wt.% of them have the boiling point range (150-370 degreesC) typical of diesel oil, Pyrolysi s gases are composed of hydrocarbons of which C-1 and C-4 are predominant, together with some CO, CO2 and SH2; they have very high gross calorific val ues (68-84 MJ m(-3)). Tyre-pyrolysis residues have equal dimensions as the original tyre portion and are easily disintegrable into black powder and st eel cords. The black powder has surface areas comparable to those of commer cial carbon blacks, but it has a great proportion of ash and impurities (si milar to 12 wt.%), which are the inorganic fillers added to tyre rubber; it may have a potential use as semireinforcing or nonreinforcing carbon black . (C) 2001 Elsevier Science B.V. All rights reserved.