Palladium catalysts automobile exhaust emissions

In the US and Japan automobile exhaust catalysts containing the noble metals platinum, palladium and rhodium are being used for the control of carbon monoxide, hydrocarbons, and nitrogen oxides in order to satisfy regulatory emission control requirements and such catalysts will be introduced in Europe in the near future. 

Platinum group elements (PGE) are used as catalysts in a variety of industrial, chemical and pharmaceutical applications, such as in the production of pesticides and dye stuffs and in the processing of polymers. These rare noble metals, notably platinum (Pt), rhodium (Rh) and palladium (Pd), are also used as catalysts in automobile catalytic converters to reduce the emission of carbon monoxide (CO), nitrogen oxides (NOJ and hydrocarbons (HC) in exhaust fumes. This application, in fact, accounts for the largest consumption of the global supply of these metals on a per weight basis. In 2008, for instance, catalytic converter producers consumed a total of 52, 47 and 86% of the world s Pt, Pd and Rh, respectively (Matthey 2008). Pd use by the catalyst industry increased by a factor of six from 1993 to 2008 (Matthey 1996, 2008). 

In the United States, The Clean Air Act of 1970 mandated the reduction of automotive pollutant emissions. The most effective way to accomplish the reduction of emissions was through the use of a catalytic converter. It s shaped like a muffler and connected to the exhaust system of an automobile. It has a solid catalyst, either palladium or platinum, inside. When the exhaust gases pass over the catalyst, the catalytic converter helps to complete the oxidation of the hydrocarbons and carbon monoxide to carbon dioxide and water. In other words, it helps to change the harmful gases from gasoline to mostly harmless products. 

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