MICROCALORIMETRIC STUDY OF OXYGEN-ADSORPTION ON CATALYTICALLY PROMOTED GASIFICATION CHARS - MECHANISTIC EVIDENCE FOR ALKALI-EARTH-METAL AND ALKALINE-EARTH-METAL CARBONATE CATALYZED-REACTIONS

A series of microcalorimetric studies have been undertaken in order to better understand the mechanism of catalytic coal char gasification by alkali-metal and alkaline-earth-metal catalysts. The present work is a report on a study of the interaction between oxygen and coal chars promoted with either sodium or magnesium carbonate. Results suggest that the active phase of sodium is a highly dispersed metallic phase. This contrasts with earlier studies on the behavior of alkali-metal catalysts in which it was found that potassium is in a partially oxidized state and even more highly dispersed. This indicates that not all alkali metals promote coal char gasification through the same mechanism. It was also found that magnesium did not wet the char surface and failed to adsorb a significant quantity of oxygen. This is consistent with earlier studies on the behavior of alkali-earth-metal char catalysts.