B+-+Catalytic+Converter

Jose del Castillo Wednesday October 27, 2010

A catalytic converter is a device that removes pollutants from the exhaust of an internal combustion engine. Invented by Eugene Houdry i n the 1950’s, it was first widely introduced to cars in 1975. **Construction:** -The Catalytic converter is made up of 3 components the core, the washcoat, and the catylist. -The core is ceramic or stainless steel honeycomb used to increase the surface area supporting the catalyst therefore increasing the efficiency of the catalytic converter. -The honeycomb shape also aligns the air in a straight line with reduces turbulence and increases the efficiency of the exaust system. -The washcoat of alumina(Al2O3) and silica(SiO2) is added to the core to make a rought surface with far greater surface area than the flat core which allows for more places for active precious metal sites. -The catalyst is added to the washcoat before it’s applied to the core. -The catalyst is usually a precious metal or metals that helps the reaction of harmful toxins into less toxic substances. Platinum and rhodium are used are used as a reduction catalyst and platinum and palladium as an oxidation catalyst. -There are two types of catalytic converters, two way and three way. -The two way catalytic converters are used for two tasks. -The oxidation of carbon from CO to CO2: 2CO + O2 → 2CO2 -The oxidation of carbon in unburned hydrocarbons into CO2: 2CO + O2 → 2CO2 -The three way catalytic converters do three tasks. It works most effectively when the engine is running slightly above the stoichiometric po int. For gasoline this comes to an air-to-fuel mixture of around 14.7:1. If the required ratio for the type of fuel varies slightly, the efficiency of the conversions is severely lowered. When the engine is running lean, with more oxygen, the oxidation is favoured at the expense of the reduction. While if the engine is running rich, more fuel, then the reduction reaction is favoured.  - The oxidation of carbon from CO to CO2: 2CO + O2 → 2CO2 - The oxidation of carbon in unburned hydrocarbons into CO2: 2CO + O2 → 2CO2 -The reduction nitrogen in nitrogen oxides to N2: 2NOx → xO2 + N2 
 * How does the Catalytic Converter in a Car? **
 * Types: **

**- The requirement of a burn near the stoichiometric point forces engines to use more fuel than they should. Gasoline engines are able to run at a 20:1 air-to-fuel mixture. But that ratio would make it harder to control the NOx emissions. -The catalytic converters work best when hot so they require a warm-up period in which the car puts out most of its pollution. In addition, diesel engines run cooler than gasoline engines which reduces the efficiency of the reduction catalyst in the catalytic converters so they don’t reduce much f the NOx. (To reduce the warm-up time pre-heaters have been installed to the catalytic converters. Unfortunately the 12 volt battery doesn’t provide enough power to heat the catalytic converter quickly. In diesel engines a urea solution is sprayed into the exhaust system just before the catalytic converter to mix with the exhaust and create a chemical reaction that reduces the NOx. This reaction produced nitrogen and water vapour. Through this method 90% of the nitrogen oxides are removed from the exhaust gases.) -Due to the increase in price of precious metals, there has been a spike in the thefts of catalytic converters from vehicles with more ground clearance such as SUV’s and trucks.
 * Problems:(solutions)

[Untitled photograph of the location of a catalytic converter]. Retrieved Oct. 5, 2006, from: <span style="line-height: normal; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; vertical-align: top;"><span style="font-family: 'Times New Roman',serif;">AccessScience | Encyclopedia Article | Catalytic converter. (n.d.). //McGraw-Hill's AccessScience Encyclopedia of Science & Technology Online//. Retrieved October 2, 2010, from [] <span style="line-height: normal; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; vertical-align: top;"><span style="font-family: 'Times New Roman',serif;">Catalytic converter - Wikipedia, the free encyclopedia. (n.d.).//Wikipedia, the free encyclopedia//. Retrieved October 2, 2010, from http://en.wikipedia.org/wiki/Catalytic_converter <span style="font-family: "Times New Roman","serif";">Anglin, D. L. (2010). Catalytic Converter. //<span style="font-family: "Times New Roman","serif";">Grolier Multimedia Encyclopedia. // <span style="font-family: "Times New Roman","serif";">Retrieved October 3, 2010, from Grolier Online http://gme.grolier.com/article?assetid=0054700-0 <span style="font-family: "Times New Roman","serif";"> Nice, K. (n.d.). HowStuffWorks "How Catalytic Converters Work". //<span style="font-family: "Times New Roman","serif";">Howstuffworks "Auto " //<span style="font-family: "Times New Roman","serif";">. Retrieved October 3, 2010, from []  <span style="font-family: "Times New Roman","serif";">
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