Steam activation of tyre pyrolytic carbon black:: Kinetic study in a thermobalance

Kinetic parameters for the steam activation of tyre pyrolytic carbon black have been determined by thermogravimetric analysis (TGA). Pyrolytic carbon black is a mainly macro and mesoporous material whose surface area can be improved via gasification to obtain microporous activated carbons. The pyrolytic carbon black sample was produced in an experimental-scale assembly where shredded tyre was pyrolysed under controlled conditions in a fixed bed reactor. Then, the activation of the resulting solid was studied by TGA using steam as activating agent. Kinetic regime was ensured fixing experimental conditions and therefore, avoiding internal and external mass transfer and heat transmission phenomena. Temperature (850-950 degrees C) and activating gas concentration (10-40 vol.%) were the influencing variables under study. This is the first time that the random pore model (RPM) has been used to fit experimental data of the activation of pyrolytic carbon black with steam. Excellent fittings have been obtained because of the special applicability of this model to predict the behaviour of solid-fluid reactive systems, in which the solid phase shows a porous structure. Reaction evolution has successfully been modelled, including the maximum reaction rate obtained in experimental results. Additionally, intrinsic kinetic parameters of the activation reaction-reaction order, activation energy and pre-exponential factor - were calculated. (c) 2006 Elsevier B.V. All rights reserved.