A method of forming high molecular weight (“HMW”) coal tar can include combining supercritical carbon dioxide (sCO.sub.2) and an amount of coal tar, and fractionating the amount of coal tar to form the HMW coal tar. The method can further include forming the amount of coal tar from coal. Forming the amount of coal tar from coal can include extracting the coal tar from an amount of coal using sCO.sub.2.

A method of forming high molecular weight (“HMW”) coal tar can include combining supercritical carbon dioxide (sCO.sub.2) and an amount of coal tar, and fractionating the amount of coal tar to form the HMW coal tar. The method can further include forming the amount of coal tar from coal. Forming the amount of coal tar from coal can include extracting the coal tar from an amount of coal using sCO.sub.2.

A method of forming high molecular weight (“HMW”) coal tar can include combining supercritical carbon dioxide (sCO.sub.2) and an amount of coal tar, and fractionating the amount of coal tar to form the HMW coal tar. The method can further include forming the amount of coal tar from coal. Forming the amount of coal tar from coal can include extracting the coal tar from an amount of coal using sCO.sub.2.

A method of forming high molecular weight (“HMW”) coal tar can include combining supercritical carbon dioxide (sCO.sub.2) and an amount of coal tar, and fractionating the amount of coal tar to form the HMW coal tar. The method can further include forming the amount of coal tar from coal. Forming the amount of coal tar from coal can include extracting the coal tar from an amount of coal using sCO.sub.2.

Embodiments of methods for improving mesophase pitch for carbon fiber production using supercritical carbon dioxide are described. The methods improve the relative amount and quality of mesophase pitch in feedstocks, such as coal tar, already having at least some mesophase pitch. One particular method includes performing a sCO2/toluene extraction on the coal tar to obtain a toluene insoluble fraction of the coal tar; mixing the toluene insoluble fraction with sCO2 to obtain a sCO2/toluene insoluble fraction mixture; and extruding the sCO2/toluene insoluble fraction mixture, thereby separating the sCO2 from the toluene insoluble fraction to obtain fibers of mesophase pitch.

To provide low CTE and low puffing needle coke more stably while dealing with changes in the properties of a feedstock. The low CTE and low puffing needle coke is obtained by mixing and coking a needle coke main feedstock of a coal tar-based heavy oil or petroleum-based heavy oil having a weak hydrogen donating property with a PDQI value expressed by equation (1) of less than 5.0, with a secondary feedstock having a strong hydrogen donating property with a PDQI value expressed by equation (1) of 5.0 or more, and calcining the obtained raw coke. [Equation (1)] PDQI=H %×10×(HNβ/H), wherein H % is a hydrogen amount (% by weight) obtained by elemental analysis, and HNβ/H is a ratio of β naphthenic hydrogen to total hydrogen measured by .sup.1H-NMR.

Embodiments of methods for improving mesophase pitch for carbon fiber production using supercritical carbon dioxide are described. The methods improve the relative amount and quality of mesophase pitch in feedstocks, such as coal tar, already having at least some mesophase pitch. One particular method includes performing a sCO2/toluene extraction on the coal tar to obtain a toluene insoluble fraction of the coal tar; mixing the toluene insoluble fraction with sCO2 to obtain a sCO2/toluene insoluble fraction mixture; and extruding the sCO2/toluene insoluble fraction mixture, thereby separating the sCO2 from the toluene insoluble fraction to obtain fibers of mesophase pitch.

Embodiments of methods for improving mesophase pitch for carbon fiber production using supercritical carbon dioxide are described. The methods improve the relative amount and quality of mesophase pitch in feedstocks, such as coal tar, already having at least some mesophase pitch. One particular method includes performing a sCO2/toluene extraction on the coal tar to obtain a toluene insoluble fraction of the coal tar; mixing the toluene insoluble fraction with sCO2 to obtain a sCO2/toluene insoluble fraction mixture; and extruding the sCO2/toluene insoluble fraction mixture, thereby separating the sCO2 from the toluene insoluble fraction to obtain fibers of mesophase pitch.

Embodiments of methods for improving mesophase pitch for carbon fiber production using supercritical carbon dioxide are described. The methods improve the relative amount and quality of mesophase pitch in feedstocks, such as coal tar, already having at least some mesophase pitch. One particular method includes performing a sCO2/toluene extraction on the coal tar to obtain a toluene insoluble fraction of the coal tar; mixing the toluene insoluble fraction with sCO2 to obtain a sCO2/toluene insoluble fraction mixture; and extruding the sCO2/toluene insoluble fraction mixture, thereby separating the sCO2 from the toluene insoluble fraction to obtain fibers of mesophase pitch.

A method of forming high molecular weight (HMW) coal tar can include combining supercritical carbon dioxide (sCO.sub.2) and an amount of coal tar, and fractionating the amount of coal tar to form the HMW coal tar. The method can further include forming the amount of coal tar from coal. Forming the amount of coal tar from coal can include extracting the coal tar from an amount of coal using sCO.sub.2.