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Presentation of ctalytic converter

  1. 1. Presented By: Raheela Shabbir
  2. 2.  A catalytic converter is a device used to reduce the toxicity of emissions from an internal combustion engine.  Catalytic converters are most commonly used in motor vehicle exhaust systems.  Catalytic converters are also used on generator sets, mining equipment, trucks, buses, trains, and other engine-equipped machines.  A catalytic converter provides an environment for a chemical reaction wherein toxic combustion by- products are converted to less-toxic substances.
  3. 3.  The catalytic converter was first invented by Eugene Houdry in the 1950’s.  Tetra-ethyl lead present in gasoline "poisoned" the converter by forming a coating on the catalyst's surface, effectively disabling it.  The catalytic converter was further developed by John J. Mooney and Carl D. Keith at the Engelhard Corporation, creating the first production catalytic converter in 1973.
  4. 4.  Metal-core converter  Ceramic-core converter  The core is often a ceramic honeycomb in modern catalytic converters, but stainless steel foil honeycombs are used, too.  The honey-comb surface increases the amount of surface area available to support the catalyst, and therefore is often called a "catalyst support".  A washcoat is used to make converters more efficient, often as a mixture of silica and alumina.
  5. 5.  The catalyst is added to the washcoat (in suspension) before being applied to the core.  Platinum is the most active catalyst and is widely used.  Palladium and rhodium are two other precious metals used.  Platinum and rhodium are used as a reduction catalyst.  Platinum and palladium are used as an oxidization catalyst.  Cerium, iron, manganese and nickel are also used.
  6. 6. 1. Two way Catalytic Converter  Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2  Oxidation of unburnt hydrocarbons (unburnt and partially-burnt fuel) to carbon dioxide and water. 2. Three way Catalytic converter  Reduction of nitrogen oxides to nitrogen and oxygen and same reactions as in two way converter.
  7. 7.  Catalyst poisoning occurs when the catalytic converter is exposed to exhaust containing substances that coat the working surfaces, encapsulating the catalyst so that it cannot contact and treat the exhaust.  The most notable contaminant is lead.  Any condition that causes abnormally high levels of unburned hydrocarbons — raw or partially-burnt fuel — to reach the converter will tend to significantly elevate its temperature, bringing the risk of a meltdown of the substrate and resultant catalytic deactivation and severe exhaust restriction .
  8. 8.  Reduces fuel economy of cars resulting in a greater use of fossil fuels.  Although catalytic converters are effective at removing hydrocarbons and other harmful emissions, most of exhaust gas leaving the engine through a catalytic converter is carbon dioxide (CO2), which is responsible for the green house effect.
  9. 9.  Some early converter designs created a great deal of restriction to the flow of exhaust, which negatively affected vehicle performance, drivability, and fuel economy.  It had been stated that catalytic converters are known in a lot of cases to have an excessively long warm-up time period, in a great deal of cases ranging up to thirty-minutes. CatalyticConverter 10

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