423 / | HD | CHEMISTRY OF INORGANIC COMPOUNDS |
210 | DF | MODIFYING OR REMOVING COMPONENT OF NORMALLY GASEOUS MIXTURE {11} |
242.1 | DF | .~ Sulfur or sulfur containing component {3} |
244.01 | DF | .~.~ Utilizing solid reactant or catalyst to remove or modify sulfur or sulfur containing component {5} |
244.09 | DF | .~.~.~ Catalyst {2} |
244.1 | .~.~.~.~ Transition metal or compound thereof catalyst |