PURPOSE: To prepare, at low cost, non-meso pitch suited for use in preparation of mesophase pitch for carbon fiber, by distilling petroleum pitch under reduced pressure, feeding a particular distillate together with a non-oxidizing gas into a tubular heating reactor, and performing heat treatment under predetermined conditions.
CONSTITUTION: The petroleum pitch as the by-product in the thermal catalytic cracking of a desulfurized vacuum low-boiling oil is distilled under reduced pressure, and an 85% cut distillate (initial distillate at 460°C to final distillate at 560°C, quinoline insolubles content of 0.5% or less, inorg. substance content of 0.1% or less), together with a non-oxidizing gas, is fed into a tubular heating reactor. Then, heat treatment is conducted under atmospheric or superatmospheric pressure, at 400W500°C and at an SV1/Hr (the petroleum pitch amt. to be fed into the reaction tube/the vol. of the reaction tube) of 1W8. Thus there is continuously obtd. a non-meso pitch of 100W170°C in softening point contg. no mesophase (heptane solubles content of 10W36%, benzene solubles content of 36W48%, and quinoline insolubles content of 0.8% or less).