This letter reports on the gaseous and carbon black product characteristics from nitrogen thermal plasma pyrolysis of used tires. Steam may be injected into the plasma reaction chamber with the feed particles. When tire particles are injected into the plasma, they are heated up very rapidly by the plasma, the volatile matter is released and cracked giving rise to H2, CO, C2H2 and other light hydrocarbons. H2 and CO are the main products. By steam injection, the content of H2 is increased from 14.2 to 24.1 % and CO is increased from 3.2 to 14.2%. The gas product from plasma pyrolysis with steam may be utilized in syngas applications. Tires contain approximately 25% to 30% of carbon black filler and 5% of inorganic components on a steelfree basis. The inorganic tire components usually end up in the solid residues, thus, if no carbonaceous deposits are formed, tire pyrolysis should yield approximately 30% to 35% pyrolytic carbon black (CB). High CB yields indicated the formation of carbonaceous deposits during the pyrolysis. It should be noted that without steam injection, the yield of the CB is much higher than the theoretical values expected from concentration of the virgin carbon black in the tires. With steam injection, the yield of the gas reaches up to about 77%, while the yield of the CB is about 23%, which is lower than the concentration value of the virgin carbon black in the tires. These changes indicated that there are some chemical processes occurring during plasma gasification when injecting steam, and the reaction between carbon and steam may play a significant role in the pyrolysis process, such as C + H2O-> H2 + CO. Compared with standard carbon black, the particle sizes are similar and in both cases the morphology of the carbon black changed only slightly in the thermal plasma pyrolysis process. Using X-ray photoelectron spectroscopy (XPS) PHI-5300/ESCA, wide scan spectra are dominated by the C1, photoelectron peak, representing the major constituent of the carbon black; small signals confirm that oxygen and sulfur are also present in the surface region as well as peaks of other elements such as Zn, Cu, Al. The FWHM of the C1 indicates that pyrolysic carbon black obtained from plasma pyrolysis with steam injection has a more complete graphitic structure. Probably, aliphatic or adsorbed hydrocarbon compounds on the CB surface can react with steam and thus are oxidized/removed, resulting in a higher graphitization degree of CB.
Thermal plasma pyrolysis of used tires for carbon black recovery
Thermische Plasmapyrolyse von Altreifen für die Gewinnung von Ruß
Journal of Materials Science ; 40 , 14 ; 3817-3819
2005
3 Seiten, 4 Bilder, 2 Tabellen, 8 Quellen
Article (Journal)
English
Pyrolyse , Altreifen , Ruß , Stickstoff , Wasserdampf , Kohlenmonoxid , Ethylen , Konzentration , pyrolytischer Kohlenstoff , Vergasung , Teilchengröße , Morphologie (Körper) , Röntgenphotoelektronenspektroskopie , ESCA-Spektroskopie , Oberfläche , Sauerstoff , Schwefel , Zink , Kupfer , Aluminium , Graphit , aliphatischer Kohlenwasserstoff , Oxidation
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