Development of Mesophase from a Low-Temperature Coal Tar Pitch

In this study, a low-temperature coal tar pitch (CTP1) was subjected to carbonization in order to study the formation, growth, and development of mesophase achieved under different conditions. The results were compared to those obtained with a petroleum pitch (PP) and a conventional high-temperature coal tar pitch (CTP2). CTP1 was converted to mesophase at a considerably lower temperature, and also mesophase develops and coalesces at a markedly higher rate for this pitch. Volatile matter removal is a key factor in mesophase formation, but chemical composition also plays an important role, with substituted cata-condensed compounds constituting very reactive components in terms of anisotropic material development. More specifically, the oxygenated functional groups and aliphatic substituents facilitate the growth of mesophase. In particular, the high concentration of phenolic compounds present in CTP1 seems to contribute to the fast coalescence of mesophase spheres. The effect of several additives was also studied. Ferrocene was the most efficient in terms of mesophase formation, but simultaneously inhibiting coalescence. In contrast the use of argon pressure during carbonization promotes contact between mesophase spheres.