There are many different substances used as catalyst. Some examples are listed below.
Many solid hetergeneous catalyst substances are transition metals. The reaction occurs on the surface of the solid. The electron structure of transition metals adsorbs the reactant molecules strongly enough for them to react but not so strongly that the product molecules do not desorb.
Cobalt is a key constituent of a number of catalyst systems used worldwide for hydrotreating/hydrodesulfurization, Fischer Tropsch synthesis, and gasoline mercaptan removal (Merox). Other catalytic applications of cobalt include the monomer production for the manufacture of polyethylene terephthalate (PET) which is plastic used for beverage containers.
Precious metals are very good catalyst in many applications due to their extreme stability and inactivity toward chemical reactions. Precious metals used for catalyst include Platinum, Palladium, Rhuthenium and Silver.
One of the earliest uses of catalysts was in 1831 when Peregrin Phillips developed the use of platinum as a catalyst for production of sulfuric acid via the oxidation of SO2 in the “contact process”. This enabled the economical production of more concentrated sulfuric acid, which was critical for the growing chemical industry.