| 502 / | HD | CATALYST, SOLID SORBENT, OR SUPPORT THEREFOR: PRODUCT OR PROCESS OF MAKING |
| 100 | DF | CATALYST OR PRECURSOR THEREFOR {12} |
| 216 | DF | .~ Sulfur or compound containing same {3} |
| 217 | | .~.~ Sulfate {1} |
| 218 | DF | .~.~.~> And Group I metal containing (i.e., alkali, Ag, Au or Cu) |