Auger Electron Spectroscopy and Electron Probe Microanalysis Observations of Barium and Calcium Loaded on Amorphous Carbon under Gasification Conditions

In order to investigate the mobility and structural change of barium and calcium compounds loaded on carbon substrate in the courses of heat treatment and of gasification, AES and EPMA were employed to observe the surface structure of amorphous carbon black impregnated by barium or calcium nitrate. We found that barium species migrated into the bulk of carbon in the course of heat treatment up to 1123 K, while calcium species did not. The difference in mobility between barium and calcium species is due to the difference in the reducibility of these cations by the action of carbon in the course of heat treatment. Mineral matter was concentrated at the surface of carbon during gasification and reacted with BaCO₃ to disperse in the interior of BaCO₃ particles on the carbon surface. On the other hand, sulfur was found on the BaCO₃ surface under gasification conditions.