Heat-treatment of carbon blacks obtained by pyrolysis of used tires. Effect on the surface chemistry, porosity and electrical conductivity

摘要

Truck tire particles were pyrolysed at 490℃ at atmospheric pressure and under vacuum, respectively. The recovered pyrolytic carbon black (CB_P) was heated in a post-pyrolysis process at temperatures ranging from 670 to 860℃. The CB_P were studied in comparison to a commercial tire carbon black by low-pressure nitrogen adsorption and surface spectro-scopic methods (ESCA and SIMS). Furthermore, the CB_P properties were correlated to their electrical conductivities. During tire pyrolysis, carbonaceous deposits are formed on the CB_P surface and between the carbon black particles. These deposits have a lower polyaromatic character as compared with the surface of the commercial carbon black. Therefore, the electrical conductivity of CB_P is lower as compared with commercial blacks. Fewer deposits are formed during vacuum pyrolysis as compared with atmospheric pyrolysis. Upon heating, a portion of the deposits is desorbed and the polyaromatic character of the CB_P surface increases. The CB_P conductivity increases as well, in the case of vacuum pyrolysis CB_P, to values higher than commercial blacks.