In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.
Q: Palladium is commonly used as one of these species in most organic coupling reactions. A mixture of titanium and aluminum forms the Ziegler-Natta one used in polymerization reactions. In cars, platinum is used as one to convert carbon monoxide to carbon dioxide. Chlorofluorocarbons act as one in the breakdown of ozone in the atmosphere. These species work by lowering the activation energy of a chemical reaction, and a common industrial one is iron in the Haber-Bosch process. For 10 points, name these chemical species which speed up a reaction.
A:
Science