The different catalytic effects of Na species on char gasification and the reasons for this different

To study the effect of anion in sodium salts on catalytic gasification and provide some useful information for the recovery and reutilization of catalysts, the catalytic reactivity of Na 2 CO 3 , Na 2 SO 4 , NaNO 3 and NaCl was compared. In addition, the melting process of catalyst, mineral composition, specific surface area and CO 2 adsorption ability of chars loaded with catalyst was measured by in situ hot stage microscope, XRD, BET and TGA. Moreover, the mineral transformations of catalytic gasification ash were also investigated by FactSage. The results indicate that anions in sodium salts have a significant effect on gasification. Among them, Na 2 SO 4 and Na 2 CO 3 can greatly accelerate the catalytic gasification rate of coal char. The char loaded with Na 2 SO 4 or Na 2 CO 3 shows more specific surface area and more adsorption capacity of CO 2 than other chars. Simultaneously, the pictures captured by hot stage microscope reveal that Na 2 SO 4 and Na 2 CO 3 melt, become liquid film and then spread over char surface and neighboring particles; this facilitates the contact between carbon and catalyst and accelerates the gasification reaction. Na 2 SO 4 is suitable for catalytic gasification from the aspects of its catalytic activity and convenience of recovery and reutilization.