Catalytic Converters Essay

688 WordsApr 9, 20093 Pages
Catalytic Converters The job of a catalytic converter is to convert harmful pollutants to less harmful emissions before leaving through the car. In order to complete this task, the catalytic converter limits the air to fuel ratio. The ideal air to fuel ratio is known as the stoichiometic point. The emissions of a gasoline engine are mainly nitrogen gas (N2), carbon dioxide (CO2), and water vapor (H2O). Carbon dioxide is said to contribute to global warming. However, during the combustion of these molecules, smaller and more harmful chemicals are released. These include carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxide (NOx). A catalyst is required in the catalytic converter. There are two types of catalysts commonly found, oxidation and reduction catalysts. These catalysts are usually produced from palladium, platinum, or rhodium. A reduction catalyst reduces the NOx portion of harmful pollutants whereas the oxidation catalyst reduces hydrocarbons and CO. There are three-way catalytic converters and two-way catalytic converters. At any one time, a three-way catalytic converter is carrying out several chemical reactions. The first of these is the decomposition of nitrogen oxide (2NOX -> XO2 + N2). In addition a three-way catalytic converter completes the oxidation of carbon monoxide to carbon dioxide (2CO + O2 -> 2CO2). Also, the unburnt hydrocarbons are oxidized to carbon dioxide and water (2CxHy + {2x + y/2}O2 -> 2xCO2 + yH2O). A two-way catalytic converter has similar functions. A two-way catalytic converter eliminates the first task of decomposing nitrogen oxide, resulting in a more harmful emission. There are many negative aspects to catalytic converters. A main controversy of a catalytic converter is that it only works at very high temperatures. For the first few minutes when a car is started or warming up, toxic chemicals
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