Hydrodesulphurization of needle coke in atmospheric hydrogen flow

Abstract

Hydrodesulphurization of lump coke was studied in atmospheric hydrogen over a temperature range of 650–950 °C. Although ground cokes <74 μm in diameter were almost completely hydrodesulphurized after 6 h at 700 °C, only 23% of sulphur in lump cokes was removed at the same temperature after 10 h. Higher or lower temperatures reduced the level of desulphurization of lump coke to 10%. The pre-heat treatment at 650 °C before hydrodesulphurization at 750 °C provided a level of 30% after 6 h. Cooling to room temperature/reheating cycles during hydrodesulphurization at 700 °C increased the level to 38% after 10 h. Addition of a proper amount of steam also enhanced the hydrodesulphurization at 700 °C, providing a level of 37% after 10 h. Air gasification at around 450 °C for 90min enhanced the successive hydrodesulphurization significantly: a level as high as 70% was achieved at the 15% additional loss of carbon. Coefficients of thermal expansion of lump cokes were improved by such hydrodesulphurization.