A catalyst is a substance that alters the speed of chemical reaction while remaining chemically unchanged by the reaction. Enzymes, which are among the most powerful catalysts, play an essential role in living organisms, where they accelerate reactions that otherwise would require temperatures that would destroy most of the organic matter.
An example of a catalyst is finely divided platinum used to catalyze the reaction of carbon monoxide with oxygen to form carbon dioxide. This reaction is used in catalytic converters mounted in automobiles to eliminate carbon monoxide from the exhaust gases. Lead compounds reduce the ability of platinum to act as a catalyst; therefore, an automobile equipped with a catalytic converter for emission control must be fueled with unleaded gasoline.
Catalysts are of major importance in today’s industrial world. It has been estimated that about 20 percent of the U.S. gross national product is generated through the use of catalytic processes. One current area of active research in catalysis is that of enzymes. Natural enzymes have long been used by a few industries, but fewer than 20 such enzymes are presently available in industrial amounts. Biotechnologists are seeking ways in which to expand this resource and also to develop semisynthetic enzymes for highly specific tasks.