In the present study, pyrolyzed fuel oil (PFO)-based pitch without impurities was used to prepare coke under pressure, and the preparation yield and the powder resistance depending on the graphitization were investigated. The preparation yield of green coke by pressurized coking at 500 °C was about 26–27% higher than that at normal pressure. However, the coke yield after the thermal treatment of green coke at 900 °C was lower by 10.6–14.8% at the pressurization conditions than under normal pressure. This may be because the substances that are not vaporized under the pressurized conditions remain in the reactants and then are discharged later. The coke yield after the thermal treatment at 900 °C was higher by 14.9–28.3% under the pressurized conditions than under the normal pressure, indicating that the low-boiling point materials of the pitch participated more in coke polymerization under the pressurized conditions. The density of the coke prepared under the pressurized conditions was lower than that of the coke prepared under normal pressure, because the low-boiling point materials of the pitch participated in the reaction. However, after graphitization, the density values became similar (2.27–2.26 g/cm3). The volume resistivity of the graphitized samples was in a range of 0.499 × 10–2–0.384 × 10–2 Ω cm, indicating that the coke samples have similar electrical properties. The results of the present study show that, in comparison with the conventional normal-pressure process, the pressurized coking process can improve the yield through the participation of low-boiling point materials in the polymerization reaction, while maintaining the properties of the prepared coke and graphite, such as the conductivity and density.

    Abstract
    1 Introduction
    2 Experimental
        2.1 Preparation of PFO-based pitch
        2.2 Pressurized coking process
        2.3 Characterization
    3 Results and discussion
        3.1 Polymerization characteristics of petroleum residue PFO
        3.2 Characteristics of pitch depending on softening point
        3.3 Yield and physical characteristics of coke produced by pressurized coking
        3.4 Electrical characteristics of graphite powder
    4 Conclusion
    Acknowledgements 
    References

• Jong Hoon Cho(Carbon Industry Frontier Research Center, Korea Research Institute of Chemical Technology (KRICT), Department of Chemical Engineering and Applied Chemistry, Chungnam National University)
• Byong Chol Bai(Korea Institute of Convergence Textile)