| 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} |
| 423 | DF | .~.~.~ Adding nongaseous inorganic, or inorganic yielding component, prior to or during process {4} |
| 426 | | .~.~.~.~ Acid |