208 / | HD | MINERAL OILS: PROCESSES AND PRODUCTS |
177 | DF | REFINING {23} |
208 R | DF | .~ Sulfur removal (free or combined sulfur) {17} |
209 | DF | .~.~ With hydrogen {4} |
213 | DF | .~.~.~ With solid catalyst or absorbent {4} |
216 R | .~.~.~.~ With group VI metal or compound {1} | |
216 PP | DF | .~.~.~.~.~> With specific porosity or pore volume |