Cat Cracker
A large refinery vessel for processing reduced crudes or other feed-stocks in the presence of a catalyst, as opposed to the older method of thermal cracking, which employs heat and pressure only. Catalytic cracking is generally preferred since it produces less gas and other highly volatile byproducts. It produces a motor fuel of higher octane than the thermal process.
Catalyst
A substance which promotes a chemical reaction, but does not itself enter into the reaction.
Centigrade
Temperature based on 0 for the temperature at which water freezes and 100 for the temperature at which water boils. Europeans do not accept this term for Celcius. See that term above. This term is accepted and used in North American chemical texbrooks, so which term you use may depend on your location, but both are abbreviated with a degree symbol and capital C, so at least you now know what it means.
Cetane Index
An empirical measure of ignition quality. Defined as the percentage by volume of cetane in a mixture of cetane and methyl naphthalene which has the same ignition quality when used in an engine as a fuel under test.
Cloud Point
Temperature at which wax begins to crystallize from a distillate fuel.
