Mesophase pitch derived from isotropic anthracene pitch produced catalytically with HF/BF₃

The thermal preparation of the mesophase pitch from the isotropic anthracene pitch produced catalytically from anthracene with HF/BFs was studied through both single- and two-stage heat-treatments. The single stage under vacuum provided a mesophase pitch (SMAP-2) of 100% anisotropy and excellent spinnability at yield as high as 59%. The present mesophase pitch maintained the naphthenic structure to some extent, although thermal preparation, which tends to induce dehydrogenative aromatization, was employed. The two-stage preparation, comprising heat-treatments under pressure (2.1 MPa) and then under vacuum (1 Torr, 1 Torr≈133.322 Pa) increased the yield of the mesophase pitch to 64%, The resultant mesophase pitch (TMAP) of 100% anisotropy and excellent spinnability carried fewer aliphatic groups than that of the single stage. SMAP-2 was sufficiently stabilized for 30 min at 300°C, superior to that of the mesophase pitches derived from FCC-DO and the isotropic naphthalene pitch. The complete stabilization of TMAP with a smaller aliphatic structure was achieved within a slightly longer time of 45 min. The number of aliphatic groups is closely related to the stabilization reactivity. It is worth noting that the present mesophase pitches prepared from the isotropic anthracene pitch retained the structure of the starting pitch to an extent which depended on the procedure, influencing the stabilization reactivity.