Rolando Acosta, Claudia Tavera, Paola Gauthier-Maradei and Debora Nabarlatz* Production of Oil and Char by Intermediate Pyrolysis of Scrap Tyres: Influence on Yield and Product Characteristics DOI 10.1515/ijcre-2014-0137 Abstract: Scrap tyres represent a severe environmental problem that must be solved by developing technologies allowing the processing of high quantities of this residue. This work presents the results of pyrolysis oil and pyro- lytic char production by intermediate pyrolysis of rubber recovered from scrap tyres. The influence of process vari- ables such as particle size, temperature and reaction time on the characteristics of the products obtained was ana- lysed. Maximal yields of 52.56 and 39.50 wt% of pyrolysis oil and pyrolytic char, respectively, were obtained, under operational conditions that favoured the production of pyrolysis oil. The products obtained were a pyrolytic char with a maximal surface area of 85.16 m 2 /g and fixed carbon content of 78.55 wt%; and pyrolysis oil with a higher heating value of 42.94 MJ/kg, real density of 0.948 g/mL, viscosity 2.29 Â 10 -3 Pa s and acidity between 0.39 and 1.57 mg KOH/g. The highest total aro- matics (benzene, toluene, xylenes and ethylbenzene) yield in pyrolysis oil was obtained at a temperature of 466°C and volumetric gas flow of 155 NmL/min. In addi- tion, at these conditions, the pyrolysis oil having the maximum aromatic yield showed the lowest acidity. Nevertheless, it was observed that the highest pyrolysis oil yield does not necessarily lead to a higher yield of aromatics. Keywords: scrap tyres, intermediate pyrolysis, pyrolysis oil, pyrolytic char, aromatics content 1 Introduction Due to their complex chemical structure, scrap tyres are a highly pollutant solid waste, representing an economic and environmental problem in the entire world due to the difficulties in their treatment and degradation. Approximately 1 billion units per year are produced in the world, from which their annual generation is 200,000 units only in Colombia (Marin 2012). At the end of their useful life, most of them are burned without restriction, incinerated in industrial furnaces or disposed to the environment in sanitary fillings. Recycling of scrap tyres is restricted due to their complex chemical structure, because they are composed of a mixture of different elastomers, such as natural rubber, synthetic rubber (butadiene), styrene–butadiene copolymer (poly- meric matrix of the tyres) and a larger amount of che- mical additives such as black carbon, sulphur and zinc oxide (Mui, Cheung, and McKay 2010), that provide their characteristic resistance. Because natural or synthetic rubber is its major component, higher heating value (HHV) can be higher than 33 MJ/kg (Ospina and Villada 2011). Scrap tyres can be valourized by different thermochemical treatments such as incineration, pyroly- sis and gasification, being the two last technologies more efficient and environmentally friendly. Pyrolysis process by heating at temperatures between 400°C and 900°C in inert atmosphere can decompose non-biode- gradable materials and recover new products from them. The thermal degradation of the material produces a decomposition where the volatile organics (mainly rub- ber chains) are converted into gases and liquids (pyro- lysis oil and pyrolysis gas), while inorganic elements (mainly non-volatile carbon) remained as solid waste (Cano, Cerezo, and Urbina 2006). The composition of each fraction depends on the pyrolysis conditions used and on the original tyre composition. The absence of oxygen in the pyrolysis process reduces the production of pollutant gases such as NO x and SO x (Ospina and Villada 2011). The pyrolysis of scrap tyres is an endothermic pro- cess; therefore, the temperature has a significant effect *Corresponding author: Debora Nabarlatz, INTERFASE, Escuela de Ingeniería Química, Universidad Industrial de Santander, Carrera 27 # 9, Ciudadela Universitaria, Bucaramanga, Colombia AA678, E-mail: dnabarla@uis.edu.co Rolando Acosta, Claudia Tavera, Paola Gauthier-Maradei, INTERFASE, Escuela de Ingeniería Química, Universidad Industrial de Santander, Carrera 27 # 9, Ciudadela Universitaria, Bucaramanga, Colombia AA678, E-mail: racostasim@hotmail.com, clauducky_9@hotmail.com, mapaomar@uis.edu.co Int. J. Chem. React. Eng. 2015; 13(2): 189–200 Brought to you by | New York University Bobst Library Technical Services Authenticated Download Date | 6/2/15 7:42 PM