METHOD FOR PRODUCING PETROLEUM PITCH AND PETROLEUM PITCH
Petroleum pitch has a quinoline-insoluble fraction of 0.5 mass % or less, toluene-insoluble fraction of 3.0 mass % or less, softening point of 60° C. to 120° C., and viscosity at 200° C. of 200 mPa·s or less, the fixed carbon content Y (mass %) of which satisfies formula (1). A method for producing petroleum pitch includes: heat-treating petroleum heavy oil (step 1); distilling the heat-treated product obtained in step 1 and obtaining pitch 1 as a high-boiling-point component (step 2); removing the toluene-insoluble fraction from pitch 1 obtained in step 2 and obtaining a component in which the toluene-insoluble fraction has been decreased (step 3), and distilling the component in which the toluene-insoluble fraction obtained in step 3 has been decreased and obtaining pitch 2 as a high-boiling-point component (step 4). 80.0≥Y>0.2X+29.5 (1) Y: fixed carbon content (mass %), X: softening point (° C.) (60≤X≤120)
1 . A method for producing a petroleum-based pitch comprising at least the following steps 1 to 4:
step 1: subjecting a petroleum-based heavy oil to a heat treatment;
step 2: distilling the heat-treated product obtained in step 1 to obtain a pitch 1 as a high boiling point component;
step 3: removing a toluene insoluble matter (TI) from the pitch 1 obtained in step 2 to obtain a component with reduced TI; and
step 4: distilling the component with reduced toluene insoluble matter (TI) obtained in step 3 to obtain a pitch 2 as a high boiling point component.
2 . The method for producing a petroleum-based pitch according to claim 1 , wherein the petroleum-based heavy oil is ethylene bottom oil.
3 . The method for producing a petroleum-based pitch according to claim 1 , wherein the heat treatment temperature in step 1 is 360° C. to 500° C.
4 . The method for producing a petroleum-based pitch according to claim 1 , wherein the removing of the toluene insoluble matter (TI) in step 3 is carried out by adding a solvent to the pitch 1 and extracting a solvent soluble matter of the pitch 1 into the solvent, and wherein the solvent is at least one selected from the group consisting of benzene, alkylbenzene, cracked gasoline, and cracked kerosene.
5 . The method for producing a petroleum-based pitch according to claim 1 , wherein, in step 1, when the heat treatment temperature is 360° C. to 390° C., the heat treatment time is 8 hours to 48 hours; when the heat treatment temperature is more than 390° C. and 430° C. or less, the heat treatment time is 0.5 hours to 24 hours; and when the heat treatment temperature is more than 430° C. and 500° C. or less, the heat treatment time is 0.1 hours to 16 hours.
6 . A method for producing a graphite electrode, wherein the petroleum-based pitch obtained by the production method according to claim 1 is used as an impregnation pitch.
7 . A petroleum-based pitch in which a quinoline insoluble matter (QI) is 0.5% by mass or less, a toluene insoluble matter (TI) is 3.0% by mass or less, a softening point is 60° C. to 120° C., a viscosity at 200° C. is 200 mPa·s or less, and a fixed carbon content Y (% by mass) satisfies formula (1):
80.0≥ Y> 0.2 X+ 29.5 (1), wherein
Y is a fixed carbon content (% by mass), and
X is a softening point (° C.) (60≤X≤120).
8 . The petroleum-based pitch according to claim 7 , wherein the fixed carbon content is 47.0% by mass or more.
9 . The petroleum-based pitch according to claim 7 , which is an impregnation pitch for producing a carbon material.
10 . The petroleum-based pitch according to claim 9 , wherein the carbon material is a graphite electrode.