Catalytic effect of potassium on the rate of char-CO₂ gasification

The effect of potassium on the rate of char-CO₂ gasification at 800 °C was investigated. The instantaneous rate depends on both catalyst concentration ( K C) and the internal porous structure of the solid. At low values of K C atomic ratio, the rate increases sharply with the addition of catalyst. As catalyst concentration is increased, the rate first levels off and then decreases. The levelling off is attributed to the saturation of the surface with catalytic sites. The subsequent decrease in rate seems to be due to the plugging of micropores by catalyst deposits. The reaction rate changes significantly during gasification and drops sharply before gasification is completed. The drop in rate before total conversion can be explained by catalyst accumulation and pore plugging.