| 502 / | HD | CATALYST, SOLID SORBENT, OR SUPPORT THEREFOR: PRODUCT OR PROCESS OF MAKING |
| 100 | DF | CATALYST OR PRECURSOR THEREFOR {12} |
| 232 | DF | .~ Silicon containing or process of making {2} |
| 233 | DF | .~.~ Forming silica gel {2} |
| 234 | | .~.~.~ Coprecipitating {2} |
| 235 | DF | .~.~.~.~> Group III or rare earth metal, metal oxide, or metal hydroxide containing (i.e., Sc, Y, Al, Ga, In, Tl or lanthanide) |
| 236 | DF | .~.~.~.~> Group IV metal, metal oxide, or metal hydroxide, (i.e., Ti, Zr, Hf, Ge, Sn or Pb) |