The Science of Catalysts and Catalytic Converters
February 19th, 2013
Catalyst is a term that is used for a chemical agent that selectively increases the rate of a reaction without itself being affected. In the human body, enzymes are naturally occurring catalysts responsible for many essential biochemical reactions. These catalysts participate in the reactions, but are neither reactants nor products of the reaction they catalyze. The only difference between a catalyzed reaction and an uncatalyzed reaction is that the activation energy is different. There is no effect on the energy of the reactants or the products. Catalysts are usually “positive” which means that it speeds up the rate of a chemical reaction by lowering its activation energy. There are also negative catalysts or inhibitors, which slow the rate of a chemical reaction or make it less likely to occur. For an automobile’s internal combustion engine to operate, a controlled combustion reaction needs to occur inside the vehicle’s engine. But this reaction also produces harmful burnt gases that contribute significantly to air pollution. The catalytic converters in the automobile can bind with the pollutants and reduce the waste materials that cause pollution. gasoline engines, catalytic converters are reliable and efficient at reducing pollution. They convert an estimated 90% of the hydrocarbons, carbon monoxide, and nitrogen oxides produced into less harmful compounds. However, catalytic converters are less efficient when used with diesel engines, which run colder than gasoline engines. Catalytic converters work best at higher temperatures. Catalytic converters are emission-control devices that have been used in automobiles since 1975 in order to monitor carbon and greenhouse gas emissions. Modern automobiles are equipped with one that reduces emissions of three harmful compounds found in car exhaust: carbon monoxide, nitrogen oxides, and hydrocarbons. It accomplishes this through a...
Please join StudyMode to read the full document