Fig. 3b shows the BET surface area values obtained for the sample for different burn-off levels.
As observed, the evolutions are very similar, so temperature affects mainly the activation kinetics,but not porous structure development. The maximum BET areas for both temperatures studied are higher than 500 m2/g.
Concerning the BET areas published in the literature, they vary in a relatively wide range from 300 to 1000 m2/g.
These differences are a consequence of several factors, such as the experimental device used for the activation process, the original tyre characteristics,pyrolysis conditions (heating rate, secondary reactions) and other factors that may affect the char porous structure and reactivity.