Investigation of the preparation of coal tar- and petroleum-based pitch spheres and their oxidation stabilization

Oxidation-stabilized pitch spheres were prepared from pitch spheres, which were obtained by emulsifying spheroidizing mixtures of aromatic additive, such as naphthalene, and high soft-point pitch from coal and petroleum. Thermogravimetric analysis, differential gravimetric and differential scanning calorimetric analysis were employed to investigate the stabilization behavior of pitch spheres in air in relation to the type of pitch, ratios of aromatic additive to high soft-point pitch, and structures of pitch spheres. It is found that an aromatic additive can greatly reduce the softening point of pitch and promote stabilization. Petroleum pitch based spheres are more liable to oxidation compared to coal tar pitch based ones. The oxidized surface of pitch spheres acts as a diffusion barrier that inhibits the oxidation stabilization, which is alleviated by increasing the amount of aromatic additive.