The invention provides a preparation method of
petroleum-based
mesophase pitch having a uniform molecular structure and a low
softening point. The method comprises carrying out reduced pressure
distillation on catalytic
cracking oil
slurry of naphthenic
crude oil, taking a fraction having a
boiling point of 380 and 540 DEG C as a
raw material, carrying out a reaction process at a temperature of 380 to 450 DEG C under pressure of 4 MPa for 1 to 14 hours to obtain
petroleum asphalt having a
softening point of 110 to 180 DEG C, adding 1 to 15wt% of a
hydrogen donor into the
raw material, carrying out a self-pressure reaction process at 380 to 420 DEG C under
nitrogen initial pressure of 5MPa for 1 to 8h, reducing the pressure to the normal pressure, cooling the product to 350 DEG C, carrying out high purity
nitrogen purging for 0.5h to obtain hydrogenated
asphalt, and carrying out a reaction process on the hydrogenated
asphalt at 400 to 480 DEG C under pressure of 4MPa for 2 to 16h to obtain high quality
mesophase pitch. The preparation method has simple processes and realizes a low production cost. The
petroleum-based
mesophase pitch has anisotropic structure content greater than 98%, a lower
softening point of 230 to 250 DEG C, has a large basin type optical structure and good spinnability and is an excellent precursor for production of high modulus
carbon fibers.