| 502 / | HD | CATALYST, SOLID SORBENT, OR SUPPORT THEREFOR: PRODUCT OR PROCESS OF MAKING | 
| 100 | DF | CATALYST OR PRECURSOR THEREFOR {12} | 
| 300 | DF | .~ Metal, metal oxide or metal hydroxide {10} | 
| 325 | DF | .~.~ Of Group VIII (i.e., iron or platinum group) {7} | 
| 326 | DF | .~.~.~ Of platinum group metal and of iron group (i.e., Ru, Rh, Pd, Os, Ir, or Pt and Fe, Co or Ni) {1} | 
| 327 |  | .~.~.~.~ And Group III metal containing (i.e., Sc, Y, Al, Ga, In or Tl) |