| Autor: |
C.A. Mims, J.K. Pabst, R.T.K. Baker, J.J. Chludzinski |
| Rok vydání: |
1984 |
| Předmět: |
|
| Zdroj: |
Journal of Catalysis. 88:97-106 |
| ISSN: |
0021-9517 |
| DOI: |
10.1016/0021-9517(84)90054-x |
| Popis: |
Controlled atmosphere electron microscopy has been used to study the catalytic influence of potassium salts on the graphite-oxygen and graphite-steam reactions. This investigation showed strong interaction of potassium species with the graphite substrate in both reactant atmospheres. Potassium salt particles in contact with the edges of the graphite layers were observed to wet and spread on the edges at about 500 °C. Gasification then proceeded in both atmospheres by recession of the edges of the layer planes, with little or no attack by discrete catalyst particles. This behavior is consistent with previous indications of high catalyst dispersion associated with the formation of alkali surface complexes as active sites in alkali-catalyzed gasification. The technique also revealed other interesting details regarding the mode of catalyzed attack. In steam the edges show hexagonal facetting with the receding edges parallel to the 〈1120〉 set of crystal directions. This indicates a preferential reactivity in removal of the edge atoms. Occasionally portions of actively receding edges suddenly became inactive. No strong crystallographic preference or deactivation was found in the catalyzed graphite-oxygen reaction. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
