THE ROLE OF CARBON-BLACK COAL-TAR PITCH INTERACTIONS IN THE EARLY-STAGE OF CARBONIZATION

This study was undertaken to gain further insight into the types of in teraction between pitch and carbon black (CB) occurring during thermal treatment in the initial stages of carbonization, and the effects on subsequent coke structure. A commercial coal-tar pitch was blended wit h CB and then thermally treated at temperatures between 400-450 degree s C, for 5 hours-except for 430 degrees C, where the time of treatment was for 10 hours. The same thermal treatments were applied in the abs ence of CB to test the effects of temperature alone. Parent and treate d pitches were characterized by elemental analysis, optical microscopy , thermomechanical analysis (TMA) and sequential solvent extraction. A dditionally, some of the fractions were characterized by FTIR, GC and H-1-NMR. Cokes obtained at 900 degrees C were characterized by optical microscopy in terms of their porosity and optical texture. Results sh ow that the type of CB/pitch interactions are temperature dependent, t hese interactions being more significant at lower temperatures (below 425 degrees C). Hydrogenation and polymerization reactions have succes sively occurred along the range of temperatures used. CB produced an i ncrease of pitch carbon yield without affecting pitch fluidity at the lower temperatures. The effect on the reduction of coke porosity was p ronounced at the initial stages of the treatment. Coke optical texture was also affected by the presence of CB showing smaller sizes. Copyri ght (C) 1996 Elsevier Science Ltd