Novel application of red mud as disposal catalyst for pyrolysis and gasification of coal

Red mud (RM) with the high alkalinity as a catalyst was evaluated for coal pyrolysis in a fixed bed as well as CO2 gasification of its resultant char in a thermogravimetric analyzer (TGA). The addition of RM into coal could improve the quality of tar during pyrolysis and enhance the reactivity of char during gasification. For catalytic pyrolysis with 12 wt% RM at 600 °C, the light fraction in tar was 72.0 wt%, which increased by 20.0%, compared with coal pyrolysis alone. The role of metal oxides in RM on coal pyrolysis was further clarified as well. After catalytic pyrolysis with RM, the specific surface area of resultant char increased, especially for mesoporous surface area, and meanwhile the sodium in RM was proved to migrate to the char surface. These positive factors contributed to the CO2 gasification activity of char. RM with the high alkalinity showed a promising catalyst candidate for coal pyrolysis and gasification in terms of its catalytic effects and low cost.