Process for preparing mesophase pitches

A process for the preparation of a mesophase pitch, comprising

• a first step of subjecting a heavy oil of petroleum or coal origin or a heavy component obtainable by a distillation, a heat treatment or a hydro-treatment of said heavy oil, said heavy oil or said heavy component having no quinoline insoluble fraction, to a continuous heat treatment in a tubular heater at a temperature of 400.degree.-600.degree. C. under a pressure of 1 to 100 kg/cm.sup.2.G for 10 to 2000 sec and subsequently transferring the thermally treated product to a first distillation or flash distillation column, distilling or flashing it therein under a pressure of 0-3 kg/cm.sup.2.A at a temperature of 300.degree.-530.degree. C. and recovering a high softening point isotropic pitch having a softening starting temperature of 100.degree.-200.degree. C., a quinoline insoluble content of less than 2 wt% and a xylene insoluble content of more than 30 wt%, from the bottom of said column;
• a second step of subjecting said high softening point pitch to a second continuous thermal treatment in a second tubular heater in the presence of 1-5 times amount of a hydrogen-donating solvent selected from the group consisting of tetrahydroquinoline, 9,10-dihydroanthracene, hydrogenated anthracene oil, hydrogenated wash oil, hydrogenated lighter fraction of naphtha tar, hydrogenated lighter fraction of pyrolysis tar and hydrogenated lighter fraction of decant oil, at a temperature of 400.degree.-460.degree. C. under a pressure of 20-100 Kg/cm.sup.2.G for 10-120 min, so as to hydrogenate said high softening point isotropic pitch, subsequently transferring the thermally treated product to the second distillation or flash distillation column, distilling or flashing it therein at a temperature of 300.degree. C. to 530.degree. C. under a pressure of 0-3 kg/cm.sup.2.A and recovering the substantially isotropic hydrogenated pitch having a softening starting temperature of 100.degree.-200.degree. C., a quinoline insoluble content of less than 2 wt% and a xylene insoluble content of more than 30 wt%, from the bottom of said second distillation or flash distillation column;
• and
• a third step of subjecting said substantially isotropic hydrogenated pitch to a heat treatment at a temperature of 380.degree.-500.degree. C. under a reduced or atmospheric pressure to convert said substantially isotropic hydrogenated pitch to a mesophase pitch.