| 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} | 
| 180 | DF | .~.~ Elemental carbon {2} | 
| 182 | DF | .~.~.~ And metal, metal oxide, or metal hydroxide {3} | 
| 183 |  | .~.~.~.~ Of Group II (i.e., alkaline earth, Be, Mg, Zn, Cd or Hg) |