Modern methods for the desulphurisation of high sulphur content petroleum coke for use in carbon graphite materials

Objective – a review of modern desulfurization technologies for high-sulphur petroleum coke. This study will further asses their effectiveness, economic feasibility and impact on the properties of carbon materials used in the production of cold-pressed masses, aluminium electrolyser anodes and graphitized electrodes. Based on the analysis of literature sources, methods for the treatment of both coking feedstock and finished coke are considered: hydrodesulphurisation, oxidative and alkaline treatment, thermal calcination, biological leaching and hybrid technologies. Feedstock characteristics and process parameters (temperature, pressure, particle size, catalysts) were studied as well as their effect on the degree of sulphur removal and the associated structural changes in the carbon matrix. Hydrodesulphurisation of coking feedstock reduces sulphur content to 0.2–1.5%, but is costly, has low coke yield and loses effectiveness in the presence of metals in the ash. Alkaline treatment removes up to 90% of the sulphur, but increases ash content and porosity. Thermal calcination up to 1500°C removes 85% of the sulphur but leads to degradation of the carbon structure. Biological processes can be up to 92% efficient, but are time consuming. Hybrid technologies, such as vacuum heat treatment with alkaline activation, show the greatest potential for desulphurisation, achieving maximum sulphur removal efficiencies (up to 98.5%) while maintaining mechanical strength. This shows that the choice of desulphurisation method depends on the initial composition of the coke and the requirements of the final product. For example, desulphurisation of coking feedstock is economically justified for low-sulphur oils, whereas treatment of finished coke is suitable for high-sulphur materials, but reduces their density and strength. Hybrid processes that combine cleaning efficiency with minimal impact on coke structure are promising. The literature review showed that the development of low-cost catalysts, reduction of energy consumption and utilisation of sulphur containing gases are necessary for the scale-up of effective technologies.