Study on CO₂-coal gasification reaction using natural mineral catalysts

In this study, the effect of natural minerals on the reaction kinetics for lignite-CO₂ gasification was investigated. After physical mixing of lignite from Meng Tai area with 5 wt% of each natural mineral catalysts among Dolomite, Silica sand, Olivine and Kaolin, CO₂ gasification was performed using TGA at each 800, 850 °C and 900 °C. The experimental data was analyzed with volumetric reaction model (VRM), shrinking core model (SCM) and modified volumetric reaction model (MVRM). MVRM was the most suitable among three models. As increasing the reaction temperature, the reaction rate constant became higher. With natural mineral catalysts, the reaction rate constant was higher and activation energy was lower than that of without catalysts. The lowest activation energy, 114.90 kJ/mol was obtained with silica sand. The highest reaction rate constant at 850 °C and 900 °C and lower reaction rate constant at 800 °C were obtained with Kaolin. Conclusively, the better catalytic performance could be observed with Kaolin than that of using other catalysts when the reaction temperature increased.