| 502 / | HD | CATALYST, SOLID SORBENT, OR SUPPORT THEREFOR: PRODUCT OR PROCESS OF MAKING |
| 100 | DF | CATALYST OR PRECURSOR THEREFOR {12} |
| 174 | DF | .~ Inorganic carbon containing {4} |
| 177 | DF | .~.~ Carbide {1} |
| 178 | | .~.~.~ Silicon carbide {1} |
| 179 | DF | .~.~.~.~> Group VA (N, P, As, Sb, Bi) containing |