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Presenta tion on catalytic converters

  1. 1. CATALYTIC C CONVERTERS Objectives 1. What is catalytic converters 2. Uses of catalytic converters 3. Construction of catalytic converters 4. Types of catalytic converters
  2. 2. CATALYTIC CONVERTERS is a vehicle emissions control device that converts toxic pollutants in exhaust gas to less toxic pollutants by catalyzing a redox reaction (oxidation or reduction). Are used with internal combustion engines fueled by either petrol(gasoline) or diesel—including lean-burn engines. Although catalytic converters are most commonly applied to exhaust systems in automobiles, they are also used on electrical generators, forklifts, mining equipment, trucks, buses, locomotives and motorcycles.
  3. 3. CATALYTIC CONVERTERS They are also used on some wood stoves to control emissions. This is usually in response to government regulation, either through direct environmental regulation or through health and safety regulations.
  4. 4. CONSTRUCTION OF CATALYTIC CONVERTERS • They consist of many of components but we will only look at the important three. • The catalyst core or Substrate: For automotive catalytic converters, the core is usually a ceramic monolith with a honeycomb structure. • Metallic foil monoliths made of FeCrAl are used in some applications. • Either material is designed to provide a high surface area to support the catalyst washcoat, and therefore is often called a “catalyst support”. • The cordierite ceramic substrate used in most catalytic converters was invented by Rodney Bagley, Irwin Lachman and Ronald Lewis at Corning Glass, for which they were inducted into the National Inventors Hall of Fame in 2002.
  5. 5. CONSTRUCTION OF CATALYTIC CONVERTERS • The washcoat: is a carrier for the catalytic materials and is used to disperse the materials over a high surface area. • Aluminum oxide, titanium dioxide, silicon dioxide, or a mixture of silica and alumina can be used. • Washcoat materials are selected to form a rough, irregular surface, which greatly increases the surface area compared to the smooth surface of the bare substrate. • This in turn maximizes the catalytically active surface available to react with the engine exhaust. • The coat must retain its surface area and prevent sintering of the catalytic metal particles even at high temperatures (1000 °C).
  6. 6. CONSTRUCTION OF CATALYTIC CONVERTERS • The catalyst: is most often a precious metal. • Platinum is the most active catalyst and is widely used, but is not suitable for all applications. • Rhodium is used as a reduction catalyst, palladium is used as an oxidation catalyst, and platinum is used both for reduction and oxidation.
  8. 8. TYPES OF CATALYTIC CONVERTERS TWO-WAY CATALYTIC CONVERTERS • Also known as an oxidation catalytic converter has two simultaneous tasks. • Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2. • Oxidation of hydrocarbons (unburnt and partially burnt fuel) to carbon dioxide and water: CxH2x+2 + [(3x+1)/2] O2 → xCO2 + (x+1) H2O (a combustion reaction). TWO-WAY CATALYTIC CONVERTERS • Widely used on diesel engines to reduce hydro carbon and carbon monoxide emissions. • Also used on American and Canadian market automobiles until 1981. • Disadvantage: inability to control oxides of Nitrogen.
  9. 9. TYPES OF CATALYTIC CONVERTERS THREE-WAY CATALYTIC CONVERTERS • also known as oxidation and reduction catalytic converters to which the reduction and oxidation catalysts are typically contained in a common housing. • It has three simultaneous tasks: THREE-WAY CATALYTIC CONVERTERS • Reduction of nitrogen oxides to nitrogen and oxygen: 2NOx→ xO2 + N2 • Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2 • Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water: CxH2x+2 + [(3x+1)/2] O2 → xCO2 + (x+1) H2O.
  10. 10. CATALYTIC CONVERTERS By: PaulusN. Nakashole B.Sc Environmental Science 5th Sem 09/20/2015 THANK YOU!!!

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Combustible engines releases so many harmful pollutants and with the use of catalytic converters this harmful pollutants are reduced to less harmful ones.


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