The effect of inorganic compounds (e.g., Na₂CO₃, CaCl₂, FeCl₃, and H₃BO₃) on the gasification reactivity was investigated. On the one hand, coal and CO₂ gasification experiments were performed using a thermogravimetric analyzer. On the other hand, five models (Na₂CO₃-char, CaCl₂-char, FeCl₃-char, char, and H₃BO₃-char) were established in Materials Studio software due to the fact that the char gasification is the rate-determining section. Then the adsorption mechanism of gasification agent (CO₂) in the above five models was simulated using the grand canonical Monte Carlo method. After that, diffusion coefficient and adsorption activation energy were estimated. From the results of experiments, the catalytic ability followed the sequence of Na₂CO₃-coal > CaCl₂-coal > FeCl₃-coal > coal > H₃BO₃-coal. By comparing the activation energy of CO₂ adsorption in simulation, it may be noted that the sequence of CO₂ adsorption ability is the same as the inorganic compound catalytic ability. Therefore, it is inferred that the CO₂ adsorption process is the determining step in the gasification process.