| 502 / | HD | CATALYST, SOLID SORBENT, OR SUPPORT THEREFOR: PRODUCT OR PROCESS OF MAKING |
| 400 | DF | SOLID SORBENT {6} |
| 416 | DF | .~ Free carbon containing {3} |
| 418 | DF | .~.~ Process utilizing solid or liquid source carbonizable material, or product thereof {9} |
| 430 | DF | .~.~.~ Treating with gas {2} |
| 432 | | .~.~.~.~ Specified atmosphere {2} |
| 433 | DF | .~.~.~.~.~> Including free oxygen {1} |
| 435 | DF | .~.~.~.~.~> Exposure to hot flue or exhaust gas |