ORIGINAL PAPER Catalytic conversion of waste tyres into valuable hydrocarbons Jasmin Shah Æ M. Rasul Jan Æ Fazal Mabood Published online: 14 July 2007 Ó Springer Science+Business Media, LLC 2007 Abstract Tyre recycling has become a necessity because of the huge piles of tyres that represent a threat to the environment. The used tyres represent a source of energy and valuable chemical products. Waste tyres were pyrol- ysed catalytically in a batch reactor under atmospheric pressure. Calcium carbide was used as a catalyst to explore its effect on pyrolysis product distribution. The effect of temperature, amount of catalyst and time on the yields of the pyrolysed products was investigated. Char yield de- creased with increase of pyrolysis temperature while total gas and liquid yields increased. The liquid fraction was obtained with boiling point up to 320 °C. The physical and chemical properties of the pyrolysed products obtained were characterized. The catalytic pyrolysis produced 45 wt.% aromatic, 35 wt.% aliphatic and 20 wt.% of polar hydrocarbons. The distillation data showed that ~80% of oil has boil- ing point below 270 °C which is the boiling point for 50% of distilled product in commercial diesel oil. The oil frac- tion was found to have high gross calorific value; GCV (42.8 MJ kg –1 ). Its Specific gravity, viscosity, Kinematic viscosity, freezing point and diesel index were also within the limits of diesel fuel. The char residues were studied to investigate their characteristics for use as a possible adsorbent. Surface area of char before and after acid demineralization was deter- mined to determine the adsorptive features for waste water treatment. Keywords Catalytic pyrolysis Á Waste tyre Á Liquid fuel Á Calcium carbide Introduction The negative environmental impacts caused by disposal of waste automotive tyres in landfills or by incineration can be reduced by recovery of constituent chemicals and energy content by a number of available technologies. The con- ventional methods for energy recovery are based on simple combustion in cement kilns. Also, tyre powder is often used as compounding for low-value rubber goods. How- ever, all these combined applications do not solve the waste tyre-stockpiling problem and does not result in adequate profitability. Tyre pyrolysis at present is an interesting and challenging area of research. A number of studies have been reported in literature related to tyre pyrolysis for its conversion into valuable compounds. William and Brindle used fixed bed [1–3] and fluidized bed [4, 5] reactors to maximize the selective determination of single ring aromatic hydrocarbons. Lare- sgoiti et al. [6], Rodriguez et al. [7], Mastral et al. [8] and Diez et al. [9] pyrolysed waste tyres into valuable liquid fuels and compared the results of tyre oil with commercial petroleum hydrocarbons. Vacuum pyrolysis experiments were carried out by Roy et al. [10] and the data obtained indicated that the light fraction of pyrolytic oil may be used as a gasoline additives, the middle fraction as a plasticizer in rubbers and heavy fraction for the production of good quality feed stock. Roy and Chaala [11] applied the same process using high temperature and reported high heating values of the pyrolysis gases. Similarly Zolezzi et al. [12] used fast pyrolysis method and obtained high yield of oil with high heating values. J. Shah (&) Á M. R. Jan Á F. Mabood Department of Chemistry, University of Peshawar, Peshawar, N.W.F.P., Pakistan e-mail: jasminshah2001@yahoo.com 123 J Polym Environ (2007) 15:207–211 DOI 10.1007/s10924-007-0062-7